Abstract: The catalytic conversion of syngas to value-added hydrocarbons is an important strategy for the clean utilization of biomass and coal resources. Zeolites as supports and/or catalytic components are commonly used for C–C formation/cleavage in the syngas conversion, owing to their unique microporous structure, accurately tunable active sites, and molecular shape-selectivity. Herein, we have surveyed the research progress of direct conversion of syngas to hydrocarbons by using metal-loaded zeolites, bifunctional oxide-zeolite (OX-ZEO), and core-shell structured catalysts, focusing mainly on the influence of zeolite structure and acidity on the reaction mechanism as well as the product distribution for syngas conversion. In addition, an outlook is given on the perspective of zeolite synthesis and catalysis in the direct conversion of syngas.
Abstract: The light olefins, mainly ethylene, propylene and butene, are basic building blocks in chemical industry. The direct conversion of syngas to lower olefins considered as a new significant and attractive process for producing lower olefins from non-petroleum resources, owing to its process simplicity and low energy consumption. The light olefins can be directly produced from syngas via two routes, namely, the Fischer-Tropsch to olefins (FTO) reaction and oxide-zeolite (OX-ZEO) bifunctional catalysis strategy (SDTO). This paper mainly reviews recent developments of SDTO, with emphasis on the effects of catalyst design, catalyst preparation and interphase renovation on reactivity. The targeting control of operating parameters such as H2/CO ratio, temperature, pressure and contact for higher production of light olefins has also been clarified. Applications of new in situ, in real-time techniques to identify the structure-function relationship and the reaction mechanism are summarized. The recent progress including the applications of new in situ, real-time techniques to identify the structure-function relationship and the reaction mechanism are reviewed in detail. With this, the authors put forward insights into significant promising tendencies and confronting challenges in the strategy of OX-ZEO.
Abstract: One-step synthesis of light olefin and liquid fuel using syngas as platform compound is an important way to effectively utilize carbon resources. It has the characteristics of short process, low energy consumption, and is of good industrial application prospects. The one-step direct conversion of syngas to prepare light olefins and liquid fuels consists of two process routes: the Fischer-Tropsch (F-T) route and the bifunctional catalytic route. In this paper, the reaction mechanisms of both routes are briefly described. The optimal design of Fe-based and Co-based catalysts by inert supports, the effect of F-T metal particle size, reaction conditions, and catalyst structure on the catalytic performance and reaction process have been elaborated. In the bifunctional catalytic route, the influences of the CO activation components, zeolite type, the proportion and particle size of the metal oxide elements, the acidity and pore size of zeolites and the methods for coupling the CO activation components and zeolite on the performance of the catalysts were analyzed in detail. The advantages and challenges of the two routes are summarized. The development trends of efficient catalysts in the future have also been prospected.
Abstract: Aromatics, as the important industrial basic chemicals, can be prepared by direct or indirect conversion of syngas. Compared with the indirect conversion method, the direct syngas to aromatics route (STA) has the advantages of high feedstock conversion, short process, and easy product separation. In this paper, we mainly introduce the progress of research on the direct syngas to aromatics by Fischer-Tropsch route, and focus on the effects of the metal oxide coupled molecular sieve bifunctional catalysts on the catalytic reaction performance, such as the selection of Fischer-Tropsch active components and additives, molecular sieve acidity modulation and pore structure regulation; Then we summarize the influence of reaction temperature, pressure, air velocity, hydrogen to carbon ratio and other parameters on the reaction performance. At last, based on the mechanisms of STA reaction and catalyst deactivation, the method for improving the activity and stability of STA catalysts is discussed.
Abstract: Long-chain linear α-olefins (LAOs) are important industrial chemicals, which are mainly obtained from petrochemical process. With the increased impact of the greenhouse effect globally, research on CO2 control and mitigation has attracted much attention. Fischer-Tropsch synthesis (FTS) provides an alternative route to obtain LAOs. In this paper, research progress on iron-based catalysts including the roles of promoters and supports for the process of CO2 hydrogenation to LAOs are analyzed. Key factors affecting the selectivity of LAOs are discussed. Challenges and possible solutions of the reaction are summarized, and an outlook for designing high-efficient iron-based catalysts is thus presented.
Abstract: Carbon dioxide capture and utilization (CCU) is the best way to solve the problem of reducing concentration of carbon dioxide in the atmosphere, and it has a good prospect for development. On this basis, chemical researchers have explored the methods of synthesizing valuable organic compounds with CO2 as carbon source. The oxazolidinones are commonly used to synthesize drugs, and they are significant in organic synthesis as chiral molecules and intermediates. The synthetic methods of oxazolidinones have emerged in recent years. Furthermore, the methods of using carbon dioxide as a carbon source have attracted many researchers. In earlier years, people explored cycloaddition reactions of carbon dioxide and aziridines to synthesize oxazolidinones, and they took alkali metals, Cr, Al or other metals as catalysts to improve the efficiency of the reactions. Because of the cost and the principle of green synthesis, it is more suitable for large-scale reaction to select cheap and easily available ionic liquids or no catalysts. In addition, carbon dioxide and compounds such as β-amino alcohols, unsaturated amines and 1, 2-dihalohydrogenated compounds can obtain moderate or even excellent yields under different reaction conditions. In this paper, we summarized the synthetic methods of oxazolidinones using CO2 with different raw materials in recent years.
Abstract: The catalytic behavior of K/LaFeBO3 (B =Cu, Zr, Al, Mn, Ni, and Zn) perovskite catalysts prepared by sol-gel and impregnation methods was investigated for CO2 hydrogenation to light olefins. The structure of various catalysts was characterized in detail by SEM, XRD, N2 adsorption-desorption, H2-TPR, CO2-TPD, TG, and XPS analysis. With the addition of Cu and Zn, the particles size decreased with high dispersion of Fe, while the exposed basic sites increased with lower hydrogen desorption temperature. The oxygen mobility in perovskites exhibited a considerable impact on catalytic activity and olefins selectivity, which considerably increased when Fe was substituted by Cu and Zn at the B site. Olefins were formed preferentially from oxygen species of the surface lattice with low binding energies (BEs). In addition, a faster diffusion rate of oxygen would lead to an enrichment of lattice oxygen species on the surface and increase the production of olefins.
Abstract: A series of Zn-Al oxides with different Zn/Al atomic ratios were prepared by the microwave-assisted evaporation-induced self-assembly (M-EISA) method, using industrial pseudo-boehmite as aluminum source. The prepared Zn-Al oxides were physically mixed with SAPO-18 zeolite and applied in tandem reaction for direct conversion of syngas to light olefins (${\rm{C}}_2^= -{\rm{C}}_4^= $). X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption, CO and H2 temperature-programmed desorption (CO-TPD, H2-TPD) and X-ray photoelectron spectroscopy (XPS) were selected for characterization. As the increase of Zn/Al ratio, the specific surface area and pore volume of Zn-Al oxides gradually decreased, while the average pore diameter firstly increased and then decreased. Compared with the ZnAl-IP prepared by the impregnation (IP) method, the ZnAl2Ox with the Zn/Al ratio of 1∶2 had a high dispersion of Zn and formed the ZnAl2O4 spinel structure that produced more oxygen vacancies. The catalytic results showed that the activity of Zn-Al samples prepared by M-EISA method firstly increased and then decreased as the Zn/Al ratio rose, while the ${\rm{C}}_2^= -{\rm{C}}_4^= $ selectivity gradually decreased. ZnAl2Ox sample exhibited the highest CO conversion of 34.8% and almost no obvious deactivation after 50 h reaction, furthermore, its catalytic performance was much better than that of ZnAl-IP sample.
Abstract: The Cu/Zn/Al precursor by coprecipitation was treated with formic acid and then calcined in N2 to obtain Cu-ZnO-Al2O3 catalyst (CZA) for the CO2 hydrogenation to methanol. XRD, BET, TG-DSC, SEM, H2-TPR, N2O titration, XPS-AES and CO2-TPD characterization techniques were used to analyze the phase composition, structural properties of the catalyst, the Cu specific surface area, the dispersion and valence of the Cu species. The results showed that the formic acid treatment tuned the ratio of Cu+ and Cu0, increased the number of medium-strong base sites in the catalyst, and raised the selectivity of methanol. Under reaction conditions of W/F(H2/CO2=70/23)=10 g∙h/mol, t =200 ℃ and p =3 MPa, using Cu-ZnO-Al2O3 treated under HCOOH/Cu (molar ratio) =0.8, the CO2 conversion and the methanol selectivity were 6.7% and 76.3%, respectively.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
