Supervisor：Chinese Academy of Sciences
Sponsors by：
Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
Editor-in-Chief：Fang yi tian
Email：rlhx@sxicc.ac.cn
ISSN 2097-213X
CN 14-1410/TQ
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
2024, 52(8): 1035-1044.
doi: 10.19906/j.cnki.JFCT.2024007
Abstract:
The utilization of biomass holds a great promise to partially replace the non-renewable fossil resources for the production of chemicals and materials for daily use, which could effectively mitigate the challenges associated with global resource scarcity. Furfural, a prominent biomass-derived platform compound derived from the dehydration of xylose in hemicellulose, which is widely used as the key intermediate or solvent in the petrochemicals, coating, pesticides, medicine, synthetic rubber, etc. At the same time, furfural can be converted into a series of high value-added chemicals and fuel, such as alcohols, acids, esters, nitriles, amines, and others due to its active C=O bonds and furan rings. Typical chemical reactions, such as reduction, oxidation, etherification, ammonia oxidation, reduction amination, ring rearrangements and others, are frequently used for the above conversions. Among various chemicals obtained from furfural conversions, nitrogen-containing compounds have attracted considerable attention, owing to the wide applications of such type molecules in the synthesis of drug molecules, bioplastics, and other functional materials. Therefore, using furfural as a raw material to synthesize bio-based nitrogenous compounds represents a cutting-edge research direction. In the presence of nitrogen sources, furfural can be transformed into diverse nitrogen-containing compounds through different reactions, such as reduction amination, ammonia oxidation, oxidative coupling, etc. Varied nitrogen sources (e.g. NH3, N2H4·H2O, NH4HCO2, CH3COONH4, (NH4)2CO3 and others), catalysts, reaction atmospheres, and temperatures can result in distinct target products during furfural conversions. Currently, domestic and foreign research groups have made significant progress on furfural conversions to different nitrogen-containing compounds. Therefore, this review aims to briefly outline the recent achievements in the synthesis of high-value nitrogen-containing compounds from furfural through catalytic conversions over different catalysts. The main content includes: (1) synthesizing amines by reduction aminations, e.g. primary, secondary, and tertiary amines; (2) nitriles production by ammonia oxidation; (3) producing amides by amidation; (4) preparing heterocyclic compounds, such as benzoheterocyclic, thiazole, pyrrole, indole, piperidine and pyridine via oxidative cyclization, decarbonylation-amination, reduction amination, hydrogenation, ring rearrangements. The influences of synthesis methods, catalyst types, reaction pathways, mechanisms, as well as the nitrogen sources, on product distributions were discussed in detail. Considering the pathways and products potentially affected by different nitrogen sources and reaction conditions, future breakthroughs in the synthesis of nitrogen-containing compounds from furfural can be anticipated from the following aspects: (1) By systematically considering the reaction processes and mechanisms, the construction of composite catalysts and precise adjustment of reaction conditions to integrate multiple reaction steps into one is a trend in this research area to attain more efficient and green conversion processes; (2) Combined experimental with theoretical investigations to comprehensively reveal the reaction pathways during the reaction of different nitrogen sources with furfural; (3) Exploration of new chemical conversion routes and catalysts for the production of more novel nitrogen-containing compounds, to further broaden the application areas of furfural based chemicals. In brief, this review provides a systematical review on the production of furfural based nitrogen-containing chemicals, which would benefit the communities working in biomass utilization areas, and also contribute to the establishment of knowledge of the furfural chemical family.
The utilization of biomass holds a great promise to partially replace the non-renewable fossil resources for the production of chemicals and materials for daily use, which could effectively mitigate the challenges associated with global resource scarcity. Furfural, a prominent biomass-derived platform compound derived from the dehydration of xylose in hemicellulose, which is widely used as the key intermediate or solvent in the petrochemicals, coating, pesticides, medicine, synthetic rubber, etc. At the same time, furfural can be converted into a series of high value-added chemicals and fuel, such as alcohols, acids, esters, nitriles, amines, and others due to its active C=O bonds and furan rings. Typical chemical reactions, such as reduction, oxidation, etherification, ammonia oxidation, reduction amination, ring rearrangements and others, are frequently used for the above conversions. Among various chemicals obtained from furfural conversions, nitrogen-containing compounds have attracted considerable attention, owing to the wide applications of such type molecules in the synthesis of drug molecules, bioplastics, and other functional materials. Therefore, using furfural as a raw material to synthesize bio-based nitrogenous compounds represents a cutting-edge research direction. In the presence of nitrogen sources, furfural can be transformed into diverse nitrogen-containing compounds through different reactions, such as reduction amination, ammonia oxidation, oxidative coupling, etc. Varied nitrogen sources (e.g. NH3, N2H4·H2O, NH4HCO2, CH3COONH4, (NH4)2CO3 and others), catalysts, reaction atmospheres, and temperatures can result in distinct target products during furfural conversions. Currently, domestic and foreign research groups have made significant progress on furfural conversions to different nitrogen-containing compounds. Therefore, this review aims to briefly outline the recent achievements in the synthesis of high-value nitrogen-containing compounds from furfural through catalytic conversions over different catalysts. The main content includes: (1) synthesizing amines by reduction aminations, e.g. primary, secondary, and tertiary amines; (2) nitriles production by ammonia oxidation; (3) producing amides by amidation; (4) preparing heterocyclic compounds, such as benzoheterocyclic, thiazole, pyrrole, indole, piperidine and pyridine via oxidative cyclization, decarbonylation-amination, reduction amination, hydrogenation, ring rearrangements. The influences of synthesis methods, catalyst types, reaction pathways, mechanisms, as well as the nitrogen sources, on product distributions were discussed in detail. Considering the pathways and products potentially affected by different nitrogen sources and reaction conditions, future breakthroughs in the synthesis of nitrogen-containing compounds from furfural can be anticipated from the following aspects: (1) By systematically considering the reaction processes and mechanisms, the construction of composite catalysts and precise adjustment of reaction conditions to integrate multiple reaction steps into one is a trend in this research area to attain more efficient and green conversion processes; (2) Combined experimental with theoretical investigations to comprehensively reveal the reaction pathways during the reaction of different nitrogen sources with furfural; (3) Exploration of new chemical conversion routes and catalysts for the production of more novel nitrogen-containing compounds, to further broaden the application areas of furfural based chemicals. In brief, this review provides a systematical review on the production of furfural based nitrogen-containing chemicals, which would benefit the communities working in biomass utilization areas, and also contribute to the establishment of knowledge of the furfural chemical family.
2024, 52(8): 1045-1056.
doi: 10.1016/S1872-5813(24)60445-7
Abstract:
A series of Cu/ZnO catalysts were prepared by the coprecipitation method and the effect of Cu/Zn ratio on the strong metal support interaction (SMSI) as well as its relation to the catalytic performance of Cu/ZnO in the gaseous hydrogenation of furfural to furfuryl alcohol was investigated. The H2-TPR, XRD, SEM, TEM and XPS characterization results reveal that there exists the SMSI effect in the Cu/ZnO catalyst that influences the catalyst microstructure. ZnO support, acting as a geometric modifier on the active metal Cu particles, has a significant influence on the electronic state of the surface Cu species. The strength of SMSI is related to the Cu/Zn ratio and the SMSI strength of various Cu/ZnO catalysts follows the order of 20Cu/ZnO > 40Cu/ZnO > 60Cu/ZnO > 80Cu/ZnO. Under the same reaction conditions, the lifetime of the 20Cu/ZnO catalyst with a furfural conversion of above 80% is only 5 h, in comparison with the lifetime of 28 h for the 60Cu/ZnO catalyst. That is, appropriate SMSI can enhance the stability of the Cu/ZnO catalyst in the hydrogenation of furfural to furfuryl alcohol, whereas excessive SMSI is detrimental to the catalyst activity.
A series of Cu/ZnO catalysts were prepared by the coprecipitation method and the effect of Cu/Zn ratio on the strong metal support interaction (SMSI) as well as its relation to the catalytic performance of Cu/ZnO in the gaseous hydrogenation of furfural to furfuryl alcohol was investigated. The H2-TPR, XRD, SEM, TEM and XPS characterization results reveal that there exists the SMSI effect in the Cu/ZnO catalyst that influences the catalyst microstructure. ZnO support, acting as a geometric modifier on the active metal Cu particles, has a significant influence on the electronic state of the surface Cu species. The strength of SMSI is related to the Cu/Zn ratio and the SMSI strength of various Cu/ZnO catalysts follows the order of 20Cu/ZnO > 40Cu/ZnO > 60Cu/ZnO > 80Cu/ZnO. Under the same reaction conditions, the lifetime of the 20Cu/ZnO catalyst with a furfural conversion of above 80% is only 5 h, in comparison with the lifetime of 28 h for the 60Cu/ZnO catalyst. That is, appropriate SMSI can enhance the stability of the Cu/ZnO catalyst in the hydrogenation of furfural to furfuryl alcohol, whereas excessive SMSI is detrimental to the catalyst activity.
2024, 52(8): 1057-1069.
doi: 10.19906/j.cnki.JFCT.2024014
Abstract:
With the huge demand for fossil resources and increasing energy consumption, the utilization of biomass as a renewable alternative to the production of chemicals and fuels has attracted much attention. Furfural (FFA), as an important biomass-based derived carbonyl compound, can be industrially produced on a large scale from lignocellulosic biomass feedstocks and converted into various high-value chemicals, liquid fuels, and functional materials through a variety of pathways, which is crucial for alleviating the global fossil resource crisis and achieving carbon peaking and carbon neutrality goals. Carbon dots (CDs) are a new type of zero-dimensional carbon-based nanomaterials with particle size usually less than 10 nm, whose core is usually composed of sp2 hybridized carbon, and whose surface contains abundant functional groups such as hydroxyl, amino, and carboxyl groups, which have excellent UV-visible absorption, strong proton adsorption, and good stability and hydrophilicity. The high electron-transferring property of the surface functional groups of CDs makes them excellent electron carriers and donors, especially under UV light irradiation. Especially under the irradiation of ultraviolet light, CDs can be used as a reducing agent and stabilizer to reduce metal ions to metal monomers. Zeolite molecular sieves can effectively promote the diffusion of reactants and products in the pores and improve the catalytic activity due to their highly ordered pores, large specific surface area, suitable pore size and good hydrothermal stability. Therefore, molecular sieves can be a good choice of carrier in multiphase catalysis, and their unique domain-limited environment can provide spatial confinement for metal particles to improve the resistance of metals to sintering and prevent the leaching of active metal substances during the catalytic process. Based on this, in this paper, bimetallic PdAg/CDs-ZSM-5 catalysts were prepared by reduction with zeolite molecular sieve ZSM-5 as the carrier and CDs as the reducing and stabilizing agents via UV irradiation and applied to the aqueous-phase hydrogenation-rearrangement of FFA for the preparation of cyclopentanone (CPO) reaction. The CDs and composite catalysts were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and pyridine infrared (Py-FTIR). The results showed that the CDs had good reducibility and abundant Lewis acidic sites, and were able to reduce Pd2+ and Ag+ to metal monomers and form PdAg nano-alloy structures. The effects of reaction temperature, reaction time and hydrogen pressure on the reaction performance of the aqueous-phase selective hydrogenation-rearrangement of FFA to produce CPO were investigated using PdAg/CDs-ZSM-5 as catalyst. It was shown that the synergistic effect between the suitable acidic sites on the composite catalyst and the PdAg alloy greatly promoted the rearrangement of the reaction intermediate FAL, thus selectively controlling the hydrogenation of FFA to produce FAL first and then further rearrangement to obtain CPO. 100% conversion of FFA was achieved at the reaction temperature of 160 ℃, 2 MPa H2, and the target product CPO under the reaction conditions of 4 h. The selectivity of the target product CPO was 92.6%. After reusing the catalyst for 5 times, the conversion of FFA was basically unchanged, and the selectivity of CPO only decreased by 3.6%.
With the huge demand for fossil resources and increasing energy consumption, the utilization of biomass as a renewable alternative to the production of chemicals and fuels has attracted much attention. Furfural (FFA), as an important biomass-based derived carbonyl compound, can be industrially produced on a large scale from lignocellulosic biomass feedstocks and converted into various high-value chemicals, liquid fuels, and functional materials through a variety of pathways, which is crucial for alleviating the global fossil resource crisis and achieving carbon peaking and carbon neutrality goals. Carbon dots (CDs) are a new type of zero-dimensional carbon-based nanomaterials with particle size usually less than 10 nm, whose core is usually composed of sp2 hybridized carbon, and whose surface contains abundant functional groups such as hydroxyl, amino, and carboxyl groups, which have excellent UV-visible absorption, strong proton adsorption, and good stability and hydrophilicity. The high electron-transferring property of the surface functional groups of CDs makes them excellent electron carriers and donors, especially under UV light irradiation. Especially under the irradiation of ultraviolet light, CDs can be used as a reducing agent and stabilizer to reduce metal ions to metal monomers. Zeolite molecular sieves can effectively promote the diffusion of reactants and products in the pores and improve the catalytic activity due to their highly ordered pores, large specific surface area, suitable pore size and good hydrothermal stability. Therefore, molecular sieves can be a good choice of carrier in multiphase catalysis, and their unique domain-limited environment can provide spatial confinement for metal particles to improve the resistance of metals to sintering and prevent the leaching of active metal substances during the catalytic process. Based on this, in this paper, bimetallic PdAg/CDs-ZSM-5 catalysts were prepared by reduction with zeolite molecular sieve ZSM-5 as the carrier and CDs as the reducing and stabilizing agents via UV irradiation and applied to the aqueous-phase hydrogenation-rearrangement of FFA for the preparation of cyclopentanone (CPO) reaction. The CDs and composite catalysts were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and pyridine infrared (Py-FTIR). The results showed that the CDs had good reducibility and abundant Lewis acidic sites, and were able to reduce Pd2+ and Ag+ to metal monomers and form PdAg nano-alloy structures. The effects of reaction temperature, reaction time and hydrogen pressure on the reaction performance of the aqueous-phase selective hydrogenation-rearrangement of FFA to produce CPO were investigated using PdAg/CDs-ZSM-5 as catalyst. It was shown that the synergistic effect between the suitable acidic sites on the composite catalyst and the PdAg alloy greatly promoted the rearrangement of the reaction intermediate FAL, thus selectively controlling the hydrogenation of FFA to produce FAL first and then further rearrangement to obtain CPO. 100% conversion of FFA was achieved at the reaction temperature of 160 ℃, 2 MPa H2, and the target product CPO under the reaction conditions of 4 h. The selectivity of the target product CPO was 92.6%. After reusing the catalyst for 5 times, the conversion of FFA was basically unchanged, and the selectivity of CPO only decreased by 3.6%.
2024, 52(8): 1070-1078.
doi: 10.19906/j.cnki.JFCT.2024018
Abstract:
5-hydroxymethylfurfural (HMF) is a versatile compound that has great market potential in the future chemical industry. HMF production from fructose has a problem of higher cost, while HMF production from glucose has a problem of lower yield. Therefore, the use of relatively inexpensive biomass-derived syrup to produce HMF in order to achieve industrial production is currently a research hotspot. A series of Sn-MOR catalysts were prepared by using mordenite zeolite (H-MOR) as a carrier, which was modified with acid treatment and adding tin to remove Al and replenish Sn. The Sn-MOR catalysts were characterized by X-ray diffraction (XRD), diffuse reflectance ultraviolet-visible spectra (UV-vis), ammonia temperature programmed desorption (NH3-TPD), and X-ray fluorescence spectroscopy (XRF). The characterization results showed that the Sn-MOR still maintained the crystal structure of mordenite, with changes in strength and content of acid centers, and Sn was inserted into the zeolite skeleton. Glucose and fructose were used as substrates in the catalytic reaction of unmodified H-MOR and modified Sn-MOR, and the experimental results showed that H-MOR catalyzed the dehydration reaction of glucose poorly, with a HMF yield of only 7.08%, but its catalytic performance in dehydration of fructose was better, with a HMF yield of 76.78%. The modified Sn-MOR possessed isomerization activity, which improved the reactivity of glucose dehydration with a HMF yield of 38.65%, while the modified Sn-MOR still maintained the high catalytic activity of MOR for fructose dehydration to HMF. Using sugar mixtures (mhydrated glucose∶mfructose = 1∶1) as the substrate, the reaction performance of the catalysts with different tin metal additions to H-MOR was firstly investigated, and the results showed that 3.76-Sn-MOR with 3.76% tin addition catalyzed the dehydration of the sugar mixtures better. The reaction performance of the catalyst prepared by adding tin after H-MOR acid treatment was further investigated, and the results showed that the 3.76-Sn-MOR1 prepared by acid treating H-MOR using 1 mol/L hydrochloric and adding tin could obtain better HMF yield (49.37%) and selectivity (58.09%) in dehydration of sugar mixtures. The reaction conditions were further optimized through orthogonal experiments using a 3.76-Sn-MOR1 catalyst in terms of sugar concentration, reaction temperature, catalyst dosage, and reaction time. The results showed that neither too high nor too low sugar concentration was conducive to HMF formation, and increasing temperature and catalyst dosage were conducive to HMF formation, but increasing temperature reduced the selectivity of HMF. Prolongating reaction time had little effect on improving the yield of HMF, but decreased the selectivity of HMF. The optimal reaction conditions were as follows: 1.5 g of sugar mixtures, reaction temperature of 170 ℃, catalyst dosage of 0.3 g, and reaction time of 3 h. Under the above optimal reaction conditions, the superior catalyst 3.76-Sn-MOR1 was finally applied to F55 fructose syrup, which has a dry matter ratio of glucose and fructose similar to that of sugar mixtures, and the HMF yield was 63.76%, the HMF selectivity was 69.43%, and the fructose syrup conversion was 91.82%. The catalyst was recycled five times and the HMF yield reduced to 49.50%, which still maintained a certain catalytic activity.
5-hydroxymethylfurfural (HMF) is a versatile compound that has great market potential in the future chemical industry. HMF production from fructose has a problem of higher cost, while HMF production from glucose has a problem of lower yield. Therefore, the use of relatively inexpensive biomass-derived syrup to produce HMF in order to achieve industrial production is currently a research hotspot. A series of Sn-MOR catalysts were prepared by using mordenite zeolite (H-MOR) as a carrier, which was modified with acid treatment and adding tin to remove Al and replenish Sn. The Sn-MOR catalysts were characterized by X-ray diffraction (XRD), diffuse reflectance ultraviolet-visible spectra (UV-vis), ammonia temperature programmed desorption (NH3-TPD), and X-ray fluorescence spectroscopy (XRF). The characterization results showed that the Sn-MOR still maintained the crystal structure of mordenite, with changes in strength and content of acid centers, and Sn was inserted into the zeolite skeleton. Glucose and fructose were used as substrates in the catalytic reaction of unmodified H-MOR and modified Sn-MOR, and the experimental results showed that H-MOR catalyzed the dehydration reaction of glucose poorly, with a HMF yield of only 7.08%, but its catalytic performance in dehydration of fructose was better, with a HMF yield of 76.78%. The modified Sn-MOR possessed isomerization activity, which improved the reactivity of glucose dehydration with a HMF yield of 38.65%, while the modified Sn-MOR still maintained the high catalytic activity of MOR for fructose dehydration to HMF. Using sugar mixtures (mhydrated glucose∶mfructose = 1∶1) as the substrate, the reaction performance of the catalysts with different tin metal additions to H-MOR was firstly investigated, and the results showed that 3.76-Sn-MOR with 3.76% tin addition catalyzed the dehydration of the sugar mixtures better. The reaction performance of the catalyst prepared by adding tin after H-MOR acid treatment was further investigated, and the results showed that the 3.76-Sn-MOR1 prepared by acid treating H-MOR using 1 mol/L hydrochloric and adding tin could obtain better HMF yield (49.37%) and selectivity (58.09%) in dehydration of sugar mixtures. The reaction conditions were further optimized through orthogonal experiments using a 3.76-Sn-MOR1 catalyst in terms of sugar concentration, reaction temperature, catalyst dosage, and reaction time. The results showed that neither too high nor too low sugar concentration was conducive to HMF formation, and increasing temperature and catalyst dosage were conducive to HMF formation, but increasing temperature reduced the selectivity of HMF. Prolongating reaction time had little effect on improving the yield of HMF, but decreased the selectivity of HMF. The optimal reaction conditions were as follows: 1.5 g of sugar mixtures, reaction temperature of 170 ℃, catalyst dosage of 0.3 g, and reaction time of 3 h. Under the above optimal reaction conditions, the superior catalyst 3.76-Sn-MOR1 was finally applied to F55 fructose syrup, which has a dry matter ratio of glucose and fructose similar to that of sugar mixtures, and the HMF yield was 63.76%, the HMF selectivity was 69.43%, and the fructose syrup conversion was 91.82%. The catalyst was recycled five times and the HMF yield reduced to 49.50%, which still maintained a certain catalytic activity.
2024, 52(8): 1079-1087.
doi: 10.1016/S1872-5813(24)60448-2
Abstract:
To address the issue of coking and deactivation of Zn/HZSM-5 catalysts used for light olefins aromatization, a high-temperature hydrothermal method was employed for catalyst pretreatment. The catalysts were characterized using XRD, N2 physical adsorption-desorption, NH3-TPD, Py-FTIR, XPS and TG techniques. The effect of high-temperature hydrothermal pretreatment on the catalytic performance and stability of the catalyst was investigated using ethylene aromatization as a probe reaction. The results showed that the Zn/HZSM-5 catalyst exhibited excellent catalytic performance after 48 h of high-temperature hydrothermal pretreatment. Although the conversion of ethylene slightly decreased, the catalyst lifetime was significantly extended, increasing from 72 to 216 h, while the aromatics selectivity remained above 60%. It was suggested that the hydrothermal treatment enhanced the interaction between ZnO species and Brønsted acid sites, promoting the generation of ZnOH+ species. This not only suppressed the hydrogen transfer reaction but also significantly enhanced the dehydrogenation performance of the catalyst, improving the selectivity towards hydrogen. Additionally, the catalyst exhibited increased carbon capacity and reduced carbon deposition rate after hydrothermal treatment, demonstrating excellent anti-coking properties.
To address the issue of coking and deactivation of Zn/HZSM-5 catalysts used for light olefins aromatization, a high-temperature hydrothermal method was employed for catalyst pretreatment. The catalysts were characterized using XRD, N2 physical adsorption-desorption, NH3-TPD, Py-FTIR, XPS and TG techniques. The effect of high-temperature hydrothermal pretreatment on the catalytic performance and stability of the catalyst was investigated using ethylene aromatization as a probe reaction. The results showed that the Zn/HZSM-5 catalyst exhibited excellent catalytic performance after 48 h of high-temperature hydrothermal pretreatment. Although the conversion of ethylene slightly decreased, the catalyst lifetime was significantly extended, increasing from 72 to 216 h, while the aromatics selectivity remained above 60%. It was suggested that the hydrothermal treatment enhanced the interaction between ZnO species and Brønsted acid sites, promoting the generation of ZnOH+ species. This not only suppressed the hydrogen transfer reaction but also significantly enhanced the dehydrogenation performance of the catalyst, improving the selectivity towards hydrogen. Additionally, the catalyst exhibited increased carbon capacity and reduced carbon deposition rate after hydrothermal treatment, demonstrating excellent anti-coking properties.
2024, 52(8): 1088-1094.
doi: 10.1016/S1872-5813(24)60439-1
Abstract:
Co/SiC catalysts have exhibited excellent performance in Fischer-Tropsch synthesis reaction. However, few research focuses on investigating the effect of SiC supports surface properties of on catalyst performance. In this study, ZrO2 was utilized to modify the SiC surface, leading to the preparation of a series of Co-ZrO2/SiC catalysts. The physicochemical properties of the catalyst were comprehensively analyzed by using N2 adsorption, XRD, H2-TPR, XPS analyses. Catalytic performance was evaluated using a fixed bed reactor, shedding light on the effect of ZrO2 modified SiC support on cobalt-based Fischer-Tropsch synthesis catalysts. The results indicated that ZrO2 surface modification on SiC resulted in an enhanced reduction degree of Co/SiC catalysts. Additionally, ZrO2 exhibited strong interaction with the amorphous phase on the SiC surface, thereby weakening the interaction between Co and the amorphous phase. This led to an increase in the electron density of cobalt species, consequently improving the selectivity of Co/SiC catalysts towards long-chain hydrocarbons.
Co/SiC catalysts have exhibited excellent performance in Fischer-Tropsch synthesis reaction. However, few research focuses on investigating the effect of SiC supports surface properties of on catalyst performance. In this study, ZrO2 was utilized to modify the SiC surface, leading to the preparation of a series of Co-ZrO2/SiC catalysts. The physicochemical properties of the catalyst were comprehensively analyzed by using N2 adsorption, XRD, H2-TPR, XPS analyses. Catalytic performance was evaluated using a fixed bed reactor, shedding light on the effect of ZrO2 modified SiC support on cobalt-based Fischer-Tropsch synthesis catalysts. The results indicated that ZrO2 surface modification on SiC resulted in an enhanced reduction degree of Co/SiC catalysts. Additionally, ZrO2 exhibited strong interaction with the amorphous phase on the SiC surface, thereby weakening the interaction between Co and the amorphous phase. This led to an increase in the electron density of cobalt species, consequently improving the selectivity of Co/SiC catalysts towards long-chain hydrocarbons.
2024, 52(8): 1095-1102.
doi: 10.1016/S1872-5813(24)60438-X
Abstract:
Deactivation of Cu/ZnO/Al2O3 catalysts in CO2 hydrogenation to methanol reaction is one of the main reasons limiting their application. We synthesized a series of La modified Cu/ZnO/Al2O3 catalysts by adding different contents of La to improve the stability. In the 100 h short-term stability test at 200 ℃ under 3 MPa with a GHSV of 12000 mL/(g·h) , the unmodified Cu/ZnO/Al2O3 catalysts degraded obviously over 100 h. In sharp contrast, the stability was significantly promoted by the addition of La. The best activity was achieved with 5% La added samples (4% CO2 conversion and 85% methanol selectivity), which also showed impressive stability over 1000 h except about 17% deactivation during the initial 190−220 h. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results revealed that the addition of 5% La improved the dispersion of Cu and Zn, inhibited the sintering of Cu, stabilized the Cu0/+ species and retarded oxidation of Cu in catalysts, which attributed to the high stability of the catalysts.
Deactivation of Cu/ZnO/Al2O3 catalysts in CO2 hydrogenation to methanol reaction is one of the main reasons limiting their application. We synthesized a series of La modified Cu/ZnO/Al2O3 catalysts by adding different contents of La to improve the stability. In the 100 h short-term stability test at 200 ℃ under 3 MPa with a GHSV of 12000 mL/(g·h) , the unmodified Cu/ZnO/Al2O3 catalysts degraded obviously over 100 h. In sharp contrast, the stability was significantly promoted by the addition of La. The best activity was achieved with 5% La added samples (4% CO2 conversion and 85% methanol selectivity), which also showed impressive stability over 1000 h except about 17% deactivation during the initial 190−220 h. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results revealed that the addition of 5% La improved the dispersion of Cu and Zn, inhibited the sintering of Cu, stabilized the Cu0/+ species and retarded oxidation of Cu in catalysts, which attributed to the high stability of the catalysts.
CO2 assistant oxidative dehydrogenation of isobutane to isobutene catalyzed by ZnCaZr solid solution
2024, 52(8): 1103-1114.
doi: 10.19906/j.cnki.JFCT.2024003
Abstract:
CO2-assisted oxidative dehydrogenation of isobutane to isobutene (CO2-BDH) is an environmentally friendly low-carbon dehydrogenation process, which can effectively utilize greenhouse gas CO2 while producing value-added product isobutylene. Besides, the soft oxidizing property of CO2 can break the thermodynamic limitation of dehydrogenation reaction and avoid the problem of deep oxidation, which makes isobutylene highly selective. However, its industrialization is still challenged by the lack of green and efficient catalysts. In this work, xZn-CaZr solid solution catalysts was prepared by one-pot co-precipitation method and applied to CO2-BDH reaction. The physicochemical properties of all catalysts were investigated by various means, and the structure-activity relationship and surface redox mechanism were described in combination with catalytic performance. The results show that xZn-CaZr catalysts formed solid solution structure with Zn species (6%−12%) existing in highly dispersion state, and the "confinement effect" given by mesoporous skeleton and strong metal-support interactions contributes to the stable distribution of nanoscale sites and generates more Zn-O-Zr interfaces. When excessive Zn species (16%) is added, the ZnO crystal will have obvious phase separation from the solid solution phase. The surface chemical states of different catalysts were analyzed by XPS, and it was found that the relative content of Oβ increased first and then decreased with the increase of Zn content. In addition, the surface reduction characteristics of the catalyst indicated that the promotion of an appropriate amount of Zn species can improve the mobility of lattice oxygen, thus 0.4Zn-CaZr catalyst showing the highest relative content of Oβ and the best oxygen conductivity. In the activity evaluation of different xZn-CaZr catalyst, 0.4Zn-CaZr catalyst shows the best catalytic dehydrogenation activity but its stability is poor, while 0.2Zn-CaZr catalyst has the best reaction stability. Moreover, the catalytic performance of ZnCaZr catalyst under different C4H10-CO2 ratios was also investigated, which indicated that the higher CO2 content in the feed gas was helpful to improve the catalytic stability and isobutene selectivity. Combined with the surface chemical state and carbon deposition information of the spent catalyst, it was found that the relative content of Oβ on the surface of 0.4Zn-CaZr catalyst decreases obviously, but the carbon deposition rate was slow. On the contrary, the relative content of Oβ for 0.2Zn-CaZr catalyst decreased less, but its carbon deposition rate was faster. We believe that the amount and mobility of lattice oxygen over xZn-CaZr catalysts were revealed as key factors in determining the catalytic performance. Notably, higher content and superior mobility of lattice oxygen can enhance the redox function of the solid solution catalyst itself and improve the activation performance of CO2. The strong oxygen supply capacity can ensure the continuous MvK catalytic cycle on the Zn-O-Zr interface, and avoid the deep accumulation of inert carbon deposits while improving the dehydrogenation activity of isobutane and selectivity of isobutene. This study shed lights on the further design and development of green and efficient CO2-BDH catalysts.
CO2-assisted oxidative dehydrogenation of isobutane to isobutene (CO2-BDH) is an environmentally friendly low-carbon dehydrogenation process, which can effectively utilize greenhouse gas CO2 while producing value-added product isobutylene. Besides, the soft oxidizing property of CO2 can break the thermodynamic limitation of dehydrogenation reaction and avoid the problem of deep oxidation, which makes isobutylene highly selective. However, its industrialization is still challenged by the lack of green and efficient catalysts. In this work, xZn-CaZr solid solution catalysts was prepared by one-pot co-precipitation method and applied to CO2-BDH reaction. The physicochemical properties of all catalysts were investigated by various means, and the structure-activity relationship and surface redox mechanism were described in combination with catalytic performance. The results show that xZn-CaZr catalysts formed solid solution structure with Zn species (6%−12%) existing in highly dispersion state, and the "confinement effect" given by mesoporous skeleton and strong metal-support interactions contributes to the stable distribution of nanoscale sites and generates more Zn-O-Zr interfaces. When excessive Zn species (16%) is added, the ZnO crystal will have obvious phase separation from the solid solution phase. The surface chemical states of different catalysts were analyzed by XPS, and it was found that the relative content of Oβ increased first and then decreased with the increase of Zn content. In addition, the surface reduction characteristics of the catalyst indicated that the promotion of an appropriate amount of Zn species can improve the mobility of lattice oxygen, thus 0.4Zn-CaZr catalyst showing the highest relative content of Oβ and the best oxygen conductivity. In the activity evaluation of different xZn-CaZr catalyst, 0.4Zn-CaZr catalyst shows the best catalytic dehydrogenation activity but its stability is poor, while 0.2Zn-CaZr catalyst has the best reaction stability. Moreover, the catalytic performance of ZnCaZr catalyst under different C4H10-CO2 ratios was also investigated, which indicated that the higher CO2 content in the feed gas was helpful to improve the catalytic stability and isobutene selectivity. Combined with the surface chemical state and carbon deposition information of the spent catalyst, it was found that the relative content of Oβ on the surface of 0.4Zn-CaZr catalyst decreases obviously, but the carbon deposition rate was slow. On the contrary, the relative content of Oβ for 0.2Zn-CaZr catalyst decreased less, but its carbon deposition rate was faster. We believe that the amount and mobility of lattice oxygen over xZn-CaZr catalysts were revealed as key factors in determining the catalytic performance. Notably, higher content and superior mobility of lattice oxygen can enhance the redox function of the solid solution catalyst itself and improve the activation performance of CO2. The strong oxygen supply capacity can ensure the continuous MvK catalytic cycle on the Zn-O-Zr interface, and avoid the deep accumulation of inert carbon deposits while improving the dehydrogenation activity of isobutane and selectivity of isobutene. This study shed lights on the further design and development of green and efficient CO2-BDH catalysts.
2024, 52(8): 1115-1130.
doi: 10.19906/j.cnki.JFCT.2024012
Abstract:
CO2 hydrogenation to synthesize high value-added aromatics is of great significance to alleviate the energy climate problem caused by CO2 emission. It is generally believed that the reaction course of CO2 hydrogenation of toluene coupled with alkylation to produce xylenes is as follows: firstly, CO2 reacts with H2 to produce methanol intermediates, and then the methanol intermediates react with toluene on zeolite catalysts to produce para-xylene (PX) by alkylation. According to the reaction pathway, it is necessary to construct a bifunctional catalyst with synergistic matching of the two process conditions to simultaneously realize the hydrogenation of CO2 to methanol intermediate and the alkylation of the intermediate and toluene to generate para-xylene. The ZnZrOx/ZSM-5 catalytic system, in which the ZnZrOx has strong thermal stability and CO2 activation ability, and the ZSM-5 has a good morphology selectivity for PX, is considered to be a promising CO2 hydrogenated toluene coupled alkylation catalyst. However, this system still suffers from low PX selectivity, mainly due to the presence of non-selective acidic sites on the outer surface of the zeolite or near the pore orifice, which leads to the generation of side reactions, such as deep methylation and toluene isomerization, and reduces the selectivity. In this paper, ZSM-5@Silicalite-1 zeolites were prepared by epitaxial growth of Silicalite-1 on the surface of ZSM-5 using solid-phase synthesis. At the same time, the highly active oxide ZnZrOx was prepared and physically mixed with ZSM-5@Silicalite-1 to form a ZnZrOx/ZSM-5@Silicalite-1 bifunctional catalyst to study the catalytic performance of CO2 hydrogenation coupled with toluene alkylation. Compared with the ZnZrOx/ZSM-5 catalyst, the modified zeolite improved the para-xylene (PX) selectivity. The effect of crystallization conditions (silicon source, crystallization process, and number of crystallizations) on the epitaxial growth of Silicalite-1 from ZSM-5 was investigated, as well as the effect of the thickness of the Silicalite-1 passivation layer on the performance of the reaction between carbon dioxide hydrogenation and toluene alkylation. The ZZO/1:3.5Z5-Na-SiO2 catalyst showed a toluene conversion of 12.0%, a xylene selectivity of 77.4%, and a PX selectivity of 73.4% in xylene under 400 ℃ and 3 MPa reaction conditions. The structure and acid properties of the zeolites were investigated in detail by SEM, XRD, N2 adsorption-desorption, XPS, NH3-TPD and Py-FTIR characterization, and the results show that the selectivity of para-xylene (PX) can be effectively improved by solid-phase epitaxial growth to extend the pore channels of ZSM-5, increase the diffusion resistance of m-xylene (MX) and o-xylene (OX), and passivate the acidity of the outer surface at the same time. This method abandons the disadvantage of previous modification of molecular sieves by blocking the pores to narrow the orifice, and upgrades the product selectivity while ensuring the catalyst activity.
CO2 hydrogenation to synthesize high value-added aromatics is of great significance to alleviate the energy climate problem caused by CO2 emission. It is generally believed that the reaction course of CO2 hydrogenation of toluene coupled with alkylation to produce xylenes is as follows: firstly, CO2 reacts with H2 to produce methanol intermediates, and then the methanol intermediates react with toluene on zeolite catalysts to produce para-xylene (PX) by alkylation. According to the reaction pathway, it is necessary to construct a bifunctional catalyst with synergistic matching of the two process conditions to simultaneously realize the hydrogenation of CO2 to methanol intermediate and the alkylation of the intermediate and toluene to generate para-xylene. The ZnZrOx/ZSM-5 catalytic system, in which the ZnZrOx has strong thermal stability and CO2 activation ability, and the ZSM-5 has a good morphology selectivity for PX, is considered to be a promising CO2 hydrogenated toluene coupled alkylation catalyst. However, this system still suffers from low PX selectivity, mainly due to the presence of non-selective acidic sites on the outer surface of the zeolite or near the pore orifice, which leads to the generation of side reactions, such as deep methylation and toluene isomerization, and reduces the selectivity. In this paper, ZSM-5@Silicalite-1 zeolites were prepared by epitaxial growth of Silicalite-1 on the surface of ZSM-5 using solid-phase synthesis. At the same time, the highly active oxide ZnZrOx was prepared and physically mixed with ZSM-5@Silicalite-1 to form a ZnZrOx/ZSM-5@Silicalite-1 bifunctional catalyst to study the catalytic performance of CO2 hydrogenation coupled with toluene alkylation. Compared with the ZnZrOx/ZSM-5 catalyst, the modified zeolite improved the para-xylene (PX) selectivity. The effect of crystallization conditions (silicon source, crystallization process, and number of crystallizations) on the epitaxial growth of Silicalite-1 from ZSM-5 was investigated, as well as the effect of the thickness of the Silicalite-1 passivation layer on the performance of the reaction between carbon dioxide hydrogenation and toluene alkylation. The ZZO/1:3.5Z5-Na-SiO2 catalyst showed a toluene conversion of 12.0%, a xylene selectivity of 77.4%, and a PX selectivity of 73.4% in xylene under 400 ℃ and 3 MPa reaction conditions. The structure and acid properties of the zeolites were investigated in detail by SEM, XRD, N2 adsorption-desorption, XPS, NH3-TPD and Py-FTIR characterization, and the results show that the selectivity of para-xylene (PX) can be effectively improved by solid-phase epitaxial growth to extend the pore channels of ZSM-5, increase the diffusion resistance of m-xylene (MX) and o-xylene (OX), and passivate the acidity of the outer surface at the same time. This method abandons the disadvantage of previous modification of molecular sieves by blocking the pores to narrow the orifice, and upgrades the product selectivity while ensuring the catalyst activity.
2021, 49(7): 998-1013.
doi: 10.1016/S1872-5813(21)60040-3
摘要：
利用CaO基吸附剂直接从高温烟气中捕集CO2因成本低、吸附性能好等优点成为CCUS（碳捕集、利用与封存）的重要技术之一。但CaO基吸附剂在碳酸化/煅烧吸脱附循环过程中存在易烧结的问题，导致其吸附性能急剧下降。本研究针对CaO基吸附剂全面总结了其吸附CO2的动力学、热力学及烧结机理，并重点综述了世界各国研究者在CaO基吸附剂抗烧结改性方面所做的研究，指出了各种方法的优点及其局限性。结果表明，水合作用改性可使吸附剂崩塌而获得更大的比表面积；酸溶液改性会在制备过程产生更多的气体和小分子物质提高吸附剂孔隙率；掺杂改性可以促进CaO对CO2的吸附和扩散，还可作为骨架分离CaO颗粒。经比较，掺杂改性工艺简单、性能好，是比较有前景的改性方法，以含钙固废制备抗烧结改性吸附剂是发展方向。
利用CaO基吸附剂直接从高温烟气中捕集CO2因成本低、吸附性能好等优点成为CCUS（碳捕集、利用与封存）的重要技术之一。但CaO基吸附剂在碳酸化/煅烧吸脱附循环过程中存在易烧结的问题，导致其吸附性能急剧下降。本研究针对CaO基吸附剂全面总结了其吸附CO2的动力学、热力学及烧结机理，并重点综述了世界各国研究者在CaO基吸附剂抗烧结改性方面所做的研究，指出了各种方法的优点及其局限性。结果表明，水合作用改性可使吸附剂崩塌而获得更大的比表面积；酸溶液改性会在制备过程产生更多的气体和小分子物质提高吸附剂孔隙率；掺杂改性可以促进CaO对CO2的吸附和扩散，还可作为骨架分离CaO颗粒。经比较，掺杂改性工艺简单、性能好，是比较有前景的改性方法，以含钙固废制备抗烧结改性吸附剂是发展方向。
2021, 49(2): 129-136.
doi: 10.1016/S1872-5813(21)60011-7
摘要：
气流床气化过程中产生的细渣含碳量很高，目前多以填埋的方式进行处理，将细渣用于循环流化床锅炉掺烧有望为细渣处理提供有利的技术。本研究选用宁东能源化工基地典型气化工艺GE、OMB及GSP产生的气化细渣为研究对象，利用物理吸附仪、激光拉曼及热重分析仪等仪器，系统研究了气化细渣中残炭的结构特征与燃烧特性。结果表明，原始气化细渣中的物质可分为黏结球形颗粒、多孔不规则颗粒与孤立的大球形颗粒，而酸洗后的气化细渣多以疏松细小的颗粒和多孔不规则块状颗粒存在；细渣中残炭的孔径尺寸主要分布在4−8 nm，且比表面积与残炭的活性位点大小顺序均为：GE > OMB > GSP；GE渣中残炭结构有序度最低，无定形炭结构最多，GSP则相反；GE渣中残炭燃烧速率最快，主要是由于GE渣中残炭有较大的比表面积、较多的无定形炭结构及较高的的活性位点，且GE渣中残炭的综合燃烧指数为5.26 × 10−7%2/（min2·℃3）。
气流床气化过程中产生的细渣含碳量很高，目前多以填埋的方式进行处理，将细渣用于循环流化床锅炉掺烧有望为细渣处理提供有利的技术。本研究选用宁东能源化工基地典型气化工艺GE、OMB及GSP产生的气化细渣为研究对象，利用物理吸附仪、激光拉曼及热重分析仪等仪器，系统研究了气化细渣中残炭的结构特征与燃烧特性。结果表明，原始气化细渣中的物质可分为黏结球形颗粒、多孔不规则颗粒与孤立的大球形颗粒，而酸洗后的气化细渣多以疏松细小的颗粒和多孔不规则块状颗粒存在；细渣中残炭的孔径尺寸主要分布在4−8 nm，且比表面积与残炭的活性位点大小顺序均为：GE > OMB > GSP；GE渣中残炭结构有序度最低，无定形炭结构最多，GSP则相反；GE渣中残炭燃烧速率最快，主要是由于GE渣中残炭有较大的比表面积、较多的无定形炭结构及较高的的活性位点，且GE渣中残炭的综合燃烧指数为5.26 × 10−7%2/（min2·℃3）。
2021, 49(8): 1057-1076.
doi: 10.1016/S1872-5813(21)60093-2
摘要：
Waste gasification has the potential to contribute to China’s transition towards carbon neutrality and zero waste cities via the recirculation of waste as secondary carbon feedstock for the production of chemicals with lower/and or zero carbon footprint, green hydrogen with zero carbon footprint and CO2-neutral synthetic liquid fuels. With China’s significant coal gasification capacity and associated experiences and expertise, Coal-to-X could act as a bridge to Waste-to-X for carbon intensive sectors such as the waste management, chemical production and mobility sectors. To illustrate the opportunities in these areas, this article presented highlights from dynamic global developments in waste gasification, focusing on pioneering industrial developments in Germany between 1980−2000’s as well as current international developments. Lessons learnt from previous and current waste gasification project deployment are shared and enabled the identification of problems which will have to be addressed in the transition from coal gasification towards mono-waste gasification technologies. Additionally, a qualitative evaluation of gasification technologies pointed to the strengths and weaknesses of fixed-bed, fluidized-bed and entrained-flow gasification principles in their application for waste gasification.
Waste gasification has the potential to contribute to China’s transition towards carbon neutrality and zero waste cities via the recirculation of waste as secondary carbon feedstock for the production of chemicals with lower/and or zero carbon footprint, green hydrogen with zero carbon footprint and CO2-neutral synthetic liquid fuels. With China’s significant coal gasification capacity and associated experiences and expertise, Coal-to-X could act as a bridge to Waste-to-X for carbon intensive sectors such as the waste management, chemical production and mobility sectors. To illustrate the opportunities in these areas, this article presented highlights from dynamic global developments in waste gasification, focusing on pioneering industrial developments in Germany between 1980−2000’s as well as current international developments. Lessons learnt from previous and current waste gasification project deployment are shared and enabled the identification of problems which will have to be addressed in the transition from coal gasification towards mono-waste gasification technologies. Additionally, a qualitative evaluation of gasification technologies pointed to the strengths and weaknesses of fixed-bed, fluidized-bed and entrained-flow gasification principles in their application for waste gasification.
2021, 49(9): 1294-1315.
doi: 10.1016/S1872-5813(21)60080-4
摘要：
在NH3选择性催化还原（NH3-SCR）反应中，由于具有宽温度窗口和良好的水热稳定性，金属负载型分子筛是具有广泛应用潜力的脱硝催化剂。本文综述了Cu基和Fe基分子筛催化剂在NH3-SCR领域的研究进展，总结了催化剂的结构特征和NH3-SCR性能指标，并对相应的金属活性位点和反应机理进行了归纳。此外，系统介绍了密度泛函理论（DFT）计算在NH3-SCR反应机理中的应用及反应动力学的研究方法，并对比了不同催化剂体系下的表观动力学参数，为进一步研究金属负载型分子筛催化剂的NH3-SCR反应机理提供方法与思路。
在NH3选择性催化还原（NH3-SCR）反应中，由于具有宽温度窗口和良好的水热稳定性，金属负载型分子筛是具有广泛应用潜力的脱硝催化剂。本文综述了Cu基和Fe基分子筛催化剂在NH3-SCR领域的研究进展，总结了催化剂的结构特征和NH3-SCR性能指标，并对相应的金属活性位点和反应机理进行了归纳。此外，系统介绍了密度泛函理论（DFT）计算在NH3-SCR反应机理中的应用及反应动力学的研究方法，并对比了不同催化剂体系下的表观动力学参数，为进一步研究金属负载型分子筛催化剂的NH3-SCR反应机理提供方法与思路。
2021, 49(8): 1208-1218.
doi: 10.1016/S1872-5813(21)60119-6
摘要：
The chemical and mineralogical characteristics of fly ash from a municipal solid waste incineration (MSWI) in China and the influence of processing parameters on heavy metals removal during leaching were investigated in this work. The fly ash particles had complex surface structure with limited specific surface area. The alkali chloride and metal salts in MSWI fly ash showed evidently impact on leaching efficiency. Metal leachability was related to their properties and speciation in fly ash. Water-soluble salts such as KCl, NaCl and CaCl2 in fly ash were easily washed out. In this study, removal efficiency by water washing was achieved to 93.1% for Cl, 41.4% for Na, 48.5% for K and 24.8% for Ca, respectively. Mineralogical analysis also revealed change of fly ash mineral phases and specification distribution after water washing. Under liquid to solid ratio of 40∶1 L/kg and treatment time of 120 min, the leaching process achieved high dropping yields of toxicity characteristic leaching procedure (TCLP) concentrations for Cu, Zn Cd and Pb (80%−100%), moderate dropping yields for As (30%−80%) and relatively low dropping yields of Ni (< 30%). In addition, heavy metals such as Pb and Zn in fly ash with twice water washing treatment at a low liquid-solid ratio could reach lower TCLP concentrations. The result indicated that the combination process of twice water washing and one acid washing could significantly reduce the environmental risk of MSWI fly ash.
The chemical and mineralogical characteristics of fly ash from a municipal solid waste incineration (MSWI) in China and the influence of processing parameters on heavy metals removal during leaching were investigated in this work. The fly ash particles had complex surface structure with limited specific surface area. The alkali chloride and metal salts in MSWI fly ash showed evidently impact on leaching efficiency. Metal leachability was related to their properties and speciation in fly ash. Water-soluble salts such as KCl, NaCl and CaCl2 in fly ash were easily washed out. In this study, removal efficiency by water washing was achieved to 93.1% for Cl, 41.4% for Na, 48.5% for K and 24.8% for Ca, respectively. Mineralogical analysis also revealed change of fly ash mineral phases and specification distribution after water washing. Under liquid to solid ratio of 40∶1 L/kg and treatment time of 120 min, the leaching process achieved high dropping yields of toxicity characteristic leaching procedure (TCLP) concentrations for Cu, Zn Cd and Pb (80%−100%), moderate dropping yields for As (30%−80%) and relatively low dropping yields of Ni (< 30%). In addition, heavy metals such as Pb and Zn in fly ash with twice water washing treatment at a low liquid-solid ratio could reach lower TCLP concentrations. The result indicated that the combination process of twice water washing and one acid washing could significantly reduce the environmental risk of MSWI fly ash.
2022, 50(2): 129-142.
doi: 10.1016/S1872-5813(21)60169-X
摘要：
In order to improve the tar quality by decreasing the heavy tar content and ensuring high tar yield, in-situ catalytic upgrading of tar from the integrated process of coal pyrolysis coupled with steam reforming of methane was conducted over carbon (KD-9) based Ni catalyst. The results show that at 650 °C, the tar yield of CP-SRM over 5Ni/KD-9 is 24.4%, which is a little lower than that of without catalyst, while the light tar yield (i.e.,18.9%) is 1.4 times higher than that of without catalyst, and the content of C2, C3 and C4 alkyl used as a substitute for benzene significantly increases tar yields by 0.5, 0.6 and 4.0 times, respectively. The content of phenols and naphthalenes in tar also increases dramatically after upgrading. Isotope tracer approach combined with the mass spectra of typical components was employed in exploring the mechanism of the upgrading process. The results show that 5Ni/KD-9 catalyzes coal tar cracking and SRM at the same time. Small free radicals such as ·CHx, ·H and ·OH generated by SRM can combine with free radicals from tar cracking, thus avoiding excessive cracking of tar.
In order to improve the tar quality by decreasing the heavy tar content and ensuring high tar yield, in-situ catalytic upgrading of tar from the integrated process of coal pyrolysis coupled with steam reforming of methane was conducted over carbon (KD-9) based Ni catalyst. The results show that at 650 °C, the tar yield of CP-SRM over 5Ni/KD-9 is 24.4%, which is a little lower than that of without catalyst, while the light tar yield (i.e.,18.9%) is 1.4 times higher than that of without catalyst, and the content of C2, C3 and C4 alkyl used as a substitute for benzene significantly increases tar yields by 0.5, 0.6 and 4.0 times, respectively. The content of phenols and naphthalenes in tar also increases dramatically after upgrading. Isotope tracer approach combined with the mass spectra of typical components was employed in exploring the mechanism of the upgrading process. The results show that 5Ni/KD-9 catalyzes coal tar cracking and SRM at the same time. Small free radicals such as ·CHx, ·H and ·OH generated by SRM can combine with free radicals from tar cracking, thus avoiding excessive cracking of tar.
2021, 49(2): 211-219.
doi: 10.1016/S1872-5813(21)60014-2
摘要：
采用溶胶-凝胶-超临界干燥法、水热法及共沉淀法分别合成了氧化铈气凝胶（CeO2-A）、纳米棒（CeO2-R）和纳米片（CeO2-F）。考察了不同形貌氧化铈的催化燃烧甲苯性能，通过多种方法分析表征了氧化铈样品的微观结构，讨论了不同方法制得的CeO2形貌结构对催化性能的影响。结果表明，CeO2-R和CeO2-F比表面积较低，并且仅暴露（111）晶面，催化燃烧甲苯活性较低。CeO2-A具有高比表面积和丰富的孔道结构，有利于反应物分子的吸附，而且同时暴露（100）和（111）两种活性晶面，增加了氧空位浓度（Osur/Olatt = 0.25）。此外，CeO2-A由于表面晶格氧移动性较强，有利于Ce3+/Ce4+氧化还原的循环，加快甲苯深度氧化反应的进行。因此，CeO2-A具有更加优异的催化燃烧甲苯活性，t50和t90分别为223 和239 ℃，这主要归因于其大比表面积、高暴露活性晶面以及强晶格氧迁移性。
采用溶胶-凝胶-超临界干燥法、水热法及共沉淀法分别合成了氧化铈气凝胶（CeO2-A）、纳米棒（CeO2-R）和纳米片（CeO2-F）。考察了不同形貌氧化铈的催化燃烧甲苯性能，通过多种方法分析表征了氧化铈样品的微观结构，讨论了不同方法制得的CeO2形貌结构对催化性能的影响。结果表明，CeO2-R和CeO2-F比表面积较低，并且仅暴露（111）晶面，催化燃烧甲苯活性较低。CeO2-A具有高比表面积和丰富的孔道结构，有利于反应物分子的吸附，而且同时暴露（100）和（111）两种活性晶面，增加了氧空位浓度（Osur/Olatt = 0.25）。此外，CeO2-A由于表面晶格氧移动性较强，有利于Ce3+/Ce4+氧化还原的循环，加快甲苯深度氧化反应的进行。因此，CeO2-A具有更加优异的催化燃烧甲苯活性，t50和t90分别为223 和239 ℃，这主要归因于其大比表面积、高暴露活性晶面以及强晶格氧迁移性。
2021, 49(1): 113-120.
doi: 10.1016/S1872-5813(21)60003-8
摘要：
考察了Pb对Mn-Ce/TiO2低温选择性催化还原（SCR）脱硝活性的影响，并对Pb中毒的催化剂进行了再生；结合氮吸附、SEM、XRD、FT-IR、H2-TPR和NH3-TPD等表征结果，研究了Mn-Ce/TiO2催化剂Pb中毒和再生活性恢复的原因。结果表明，Pb对Mn-Ce/TiO2催化剂脱硝活性有明显的抑制作用；当Pb的含量为11%时，Mn-Ce/TiO2催化剂在180 ℃下的脱硝效率从原来100%下降至44%。Pb在Mn-Ce/TiO2中的掺杂使得催化剂的比表面积以及活性组分Mn4+和Ce3+的含量降低，影响了氧化还原循环反应（Mn4+ + Ce3+ ↔ Mn3+ + Ce4+）的进行；此外，Pb的加入破坏了催化剂的酸性位点，阻碍了催化剂对NH3的吸附和活化。经硝酸再生后的Mn-Ce/TiO2催化剂的脱硝活性几乎完全恢复，在80–150 ℃下其脱硝活性甚至超过新鲜未中毒的催化剂，其原因主要在于硝酸再生能恢复催化剂的氧化还原能力、增大比表面积、并形成新的酸位点。
考察了Pb对Mn-Ce/TiO2低温选择性催化还原（SCR）脱硝活性的影响，并对Pb中毒的催化剂进行了再生；结合氮吸附、SEM、XRD、FT-IR、H2-TPR和NH3-TPD等表征结果，研究了Mn-Ce/TiO2催化剂Pb中毒和再生活性恢复的原因。结果表明，Pb对Mn-Ce/TiO2催化剂脱硝活性有明显的抑制作用；当Pb的含量为11%时，Mn-Ce/TiO2催化剂在180 ℃下的脱硝效率从原来100%下降至44%。Pb在Mn-Ce/TiO2中的掺杂使得催化剂的比表面积以及活性组分Mn4+和Ce3+的含量降低，影响了氧化还原循环反应（Mn4+ + Ce3+ ↔ Mn3+ + Ce4+）的进行；此外，Pb的加入破坏了催化剂的酸性位点，阻碍了催化剂对NH3的吸附和活化。经硝酸再生后的Mn-Ce/TiO2催化剂的脱硝活性几乎完全恢复，在80–150 ℃下其脱硝活性甚至超过新鲜未中毒的催化剂，其原因主要在于硝酸再生能恢复催化剂的氧化还原能力、增大比表面积、并形成新的酸位点。
2021, 49(12): 1752-1767.
doi: 10.1016/S1872-5813(21)60135-4
摘要：
近年来，利用生物质基平台化合物转化制备各种燃料及高值化学品引起研究人员的广泛关注。5-羟甲基糠醛（HMF）和糠醛（FFR）作为一类重要的生物质衍生平台化合物，分子结构中醛基和呋喃环等官能团赋予其独特的化学性质。本综述针对HMF和FFR在氢气、低碳醇、甲酸和硅烷等不同氢源中的催化加氢反应研究现状进行了阐述，对加氢转化过程中的主要影响因素如催化剂类型和反应条件以及反应机理等进行了详细分析，同时对HMF/FFR加氢转化应用研究前景进行了展望。
近年来，利用生物质基平台化合物转化制备各种燃料及高值化学品引起研究人员的广泛关注。5-羟甲基糠醛（HMF）和糠醛（FFR）作为一类重要的生物质衍生平台化合物，分子结构中醛基和呋喃环等官能团赋予其独特的化学性质。本综述针对HMF和FFR在氢气、低碳醇、甲酸和硅烷等不同氢源中的催化加氢反应研究现状进行了阐述，对加氢转化过程中的主要影响因素如催化剂类型和反应条件以及反应机理等进行了详细分析，同时对HMF/FFR加氢转化应用研究前景进行了展望。
2021, 49(11): 1609-1619.
doi: 10.1016/S1872-5813(21)60122-6
摘要：
化石资源的大量使用导致CO2的大量排放，带来了严重的环境问题。与此同时，CO2又是一种清洁、无毒的含碳资源。将CO2作为原料，直接转化制备重要化学品，不仅可以减缓温室效应，同时也是一条有效利用含碳资源制备清洁燃料和化学品的新路线。本文概述了近年来关于CO2加氢制备一些烃类化合物（主要包括甲烷、烯烃和芳烃）的相关研究进展；重点分析了CO2加氢制烃类化合物相关过程催化剂的研发状态和对催化反应机理的认识，并对CO2加氢转化利用的未来发展进行了展望。
化石资源的大量使用导致CO2的大量排放，带来了严重的环境问题。与此同时，CO2又是一种清洁、无毒的含碳资源。将CO2作为原料，直接转化制备重要化学品，不仅可以减缓温室效应，同时也是一条有效利用含碳资源制备清洁燃料和化学品的新路线。本文概述了近年来关于CO2加氢制备一些烃类化合物（主要包括甲烷、烯烃和芳烃）的相关研究进展；重点分析了CO2加氢制烃类化合物相关过程催化剂的研发状态和对催化反应机理的认识，并对CO2加氢转化利用的未来发展进行了展望。
2013, 41(08): 1003-1009.
Abstract:
2009, 37(04): 501-505.
Abstract:
