合成气制乙醇RhCu双金属催化剂活性位点的作用机制研究

王占慧; 凌丽霞; 王俊刚; 孙德魁; 侯博; 李德宝; 章日光; 王宝俊

doi:10.19906/j.cnki.JFCT.2021017

合成气制乙醇RhCu双金属催化剂活性位点的作用机制研究

doi: 10.19906/j.cnki.JFCT.2021017

1.
太原理工大学化学化工学院，山西太原 030024
2.
中国科学院山西煤炭化学研究所煤转化国家重点实验室，山西太原 030001
3.
太原理工大学煤科学与技术教育部和山西省重点实验室，山西太原 030024

基金项目: 国家自然科学基金重点项目（21736007），国家自然科学基金面上项目（21576178）和山西省回国留学人员科研项目（2016-030）资助

详细信息

通讯作者:
E-mail：linglixia@tyut.edu.cn

中图分类号: O643
计量
- 文章访问数: 246
- HTML全文浏览量: 98
- PDF下载量: 29
- 被引次数: 0
出版历程
- 收稿日期: 2020-11-03
- 修回日期: 2020-11-30
- 网络出版日期: 2021-03-19
- 刊出日期: 2021-03-19

Study on the effect of active sites of ethanol synthesis from syngas over RhCu bimetallic catalyst

1.
College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
2.
State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China
3.
Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, China

Funds: The project was supported by the National Natural Science Foundation of China (21736007), the National Natural Science Foundation of China (21576178) and Shanxi Scholarship Council of China (2016-030)

摘要

摘要: 稳定高效双金属催化剂的研究对于合成气直接合成乙醇具有重大意义，但也存在一定的挑战。本研究采用尿素辅助凝胶法和初湿浸渍法，制备了系列RhCu/P25双金属催化剂，并进行合成气直接制乙醇性能研究。研究表明，Rh改性的Cu基催化剂可以有效促进乙醇的生成，然而Rh和Cu活性位点之间紧密接触时，反应产物以甲烷和甲醇为主，乙醇含量甚微。RhCu/P25双金属催化剂反应性能的减弱与Rh和Cu活性位点上CO分子吸附受到抑制相关。当采用物理混合的方式增大Rh和Cu活性位点的空间距离时，CO分子的吸附明显增强，催化活性以及乙醇选择性提高。
- RhCu双金属催化剂 /
- 乙醇 /
- 紧密接触 /
- 空间距离 /
- 活性位点
Abstract: Developing efficient and stable bimetallic catalysts has been a highly promising challenge for the direct synthesis of ethanol from syngas in recent years. In this study, a series of RhCu/P25 bimetallic catalysts with different Rh contents were prepared by combining the urea-assisted gel method and the impregnation method, and their performance in ethanol synthesis from syngas was studied. The results show that Rh-modified Cu-based catalyst can effectively promote the ethanol production. However, when the active sites of Rh and Cu are in close contact, the reaction products are mainly methane and methanol, and ethanol content is very low. This should be attributed to the inhibition of the adsorption of CO molecules on the Rh and Cu active sites. When the spatial distance between the Rh and Cu active sites is increased by physical mixing, the adsorption of CO molecules is significantly enhanced, and the catalytic activity and ethanol selectivity are improved.
- RhCu bimetallic catalysts /
- ethanol /
- close contact /
- spatial distance /
- active sites

HTML全文

下载: 全尺寸图片幻灯片

图 1 不同Rh含量的xRh-10Cu/P25催化剂反应性能测试

Figure 1 Catalytic performance of the xRh-10Cu/P25 catalysts with different Rh contents in CO hydrogenation

下载: 全尺寸图片幻灯片

图 2 焙烧后的1.4Rh-10Cu/P25催化剂的TEM和EDS照片

Figure 2 TEM and EDS images of the calcined 1.4Rh-10Cu/P25

下载: 全尺寸图片幻灯片

图 3 载体和催化剂的XRD谱图

Figure 3 XRD patterns of the support and catalysts

下载: 全尺寸图片幻灯片

图 4 载体和催化剂的H₂-TPR谱图

Figure 4 H₂-TPR profiles of the support and catalysts

下载: 全尺寸图片幻灯片

图 5 催化剂的Cu 2p XPS谱图(a)；Cu LMM XAES谱图(b)；Rh 3d XPS谱图(c)

Figure 5 Spectra of the catalysts (a): Cu 2p XPS; (b): Cu LMM XAES; (c): Rh 3d XPS

下载: 全尺寸图片幻灯片

图 6 催化剂在CO气氛吸附30 min，Ar吹扫20 min后的原位DRIFT谱图

Figure 6 In situ DRIFT spectra of CO adsorption during CO flow for 30 min and then in the Ar for 20 min at 30 ℃ over the catalysts

下载: 全尺寸图片幻灯片

图 7 不同Rh含量催化剂的CO-TPD谱图

Figure 7 CO-TPD profiles of the catalysts with different Rh content

下载: 全尺寸图片幻灯片

图 8 不同复合方式的RhCu/P25催化剂在30 ℃下吸附CO 30 min，经Ar吹扫20 min的原位DRIFT谱图

Figure 8 In situ DRIFT spectra of CO adsorption during CO flow for 30 min and then in the Ar for 20 min at 30 ℃ over RhCu/P25 catalysts prepared with different integration manner methods

下载: 全尺寸图片幻灯片

图 9 不同复合方式的RhCu/P25催化剂的CO-TPD谱图

Figure 9 CO-TPD profiles of RhCu/P25 catalysts prepared with different integration methods

下载: 全尺寸图片幻灯片

图 10 活性组分的混合方式对于合成乙醇性能的影响（a）尿素辅助凝胶和初湿浸渍法联用将Rh和Cu活性物种化学混合在一起；（b）在研钵中将1.4Rh/P25和10Cu/P25简单混合；（c）尺寸为250−420 μm的10Cu/P25和1.4Rh/P25颗粒混合；（d）上层1.4Rh/P25，下层10Cu/P25；（e）上层10Cu/P25，下层1.4Rh/P25

Figure 10 Effect of the integration methods of active components on the performance of ethanol synthesis (a) combined urea-assisted gel with incipient wetness impregnation method for chemical mixing of Rh and Cucomponents ; (b) physical mixing of Rh and Cu components in an agate mortar; (c) stacking of 10Cu/P25 and 1.4Rh/P25 granules with sizes of 250–420 μm; (d) 1.4Rh/P25|10Cu/P25; (e) 10Cu/P25|1.4Rh/P25

下载: 全尺寸图片幻灯片

表 1 ICP测得的xRh-10Cu/P25催化剂中Rh和Cu的实际含量

Table 1 Actual content of Rh and Cu in xRh-10Cu/P25 catalysts measured by ICP

Sample	Cu loading /%^a	Rh loading /%^a
10Cu/P25	10.46	−
1.4Rh/P25	−	1.37
0.3Rh-10Cu/P25	10.03	0.28
1.4Rh-10Cu/P25	9.93	1.30
2.5Rh-10Cu/P25	9.80	2.62
3.6Rh-10Cu/P25	9.68	3.36
6.0Rh-10Cu/P25	9.92	5.89
^a: determined by ICP analysis

下载: 导出CSV

参考文献(37)

[1]	GUO S X, LI S S, ZHONG H X, GONG D D, WANG J M, KANG N, ZHANG L H, LIU G L, LIU Y. Mixed oxides confined and tailored cobalt nanocatalyst for direct ethanol synthesis from syngas: A catalyst designing by using perovskite-type oxide as the precursor[J]. Ind Eng Chem Res,2018,57(6):2404−2415. doi: 10.1021/acs.iecr.7b04336
[2]	AO M, PHAM G H, SUNARSO J, TADE M O, LIU S M. Active centers of catalysts for higher alcohol synthesis from syngas: A review[J]. ACS Catal,2018,8(8):7025−7050. doi: 10.1021/acscatal.8b01391
[3]	LUK H T, MONDELLI C, FERRE D C, STEWART J A, PEREZ-RAMIREZ J. Status and prospects in higher alcohols synthesis from syngas[J]. Chem Soc Rev,2017,46(5):1358−1426. doi: 10.1039/C6CS00324A
[4]	GU T J, WANG B C, CHEN S Y, YANG B. Automated generation and analysis of the complex catalytic reaction network of ethanol synthesis from syngas on Rh(111)[J]. ACS Catal,2020,10(11):6346−6355. doi: 10.1021/acscatal.0c00630
[5]	XIAO K, BAO Z H, QI X Z, WANG X X, ZHONG L S, FANG K G, LIN M G, SUN Y H. Advances in bifunctional catalysis for higher alcohol synthesis from syngas[J]. Chin J Catal,2013,34(1):116−129. doi: 10.1016/S1872-2067(11)60496-8
[6]	ZHU Y, KONG X, LI X, DING G, ZHU Y, LI Y W. Cu Nanoparticles inlaid mesoporous Al₂O₃ as a high-performance bifunctional catalyst for ethanol synthesis via dimethyl oxalate hydrogenation[J]. ACS Catal,2014,4(10):3612−3620. doi: 10.1021/cs5009283
[7]	PALOMINO R M, MAGEE J W, LLORCA J, SENANAYAKE S D, WHITE M G. The effect of Fe-Rh alloying on CO hydrogenation to C₂₊ oxygenates[J]. J Catal,2015,329:87−94. doi: 10.1016/j.jcat.2015.04.033
[8]	GUPTA M, SMITH M L, SPIVEY J J. Heterogeneous catalytic conversion of dry syngas to ethanol and higher alcohols on Cu-based catalysts[J]. ACS Catal,2011,1(6):641−656. doi: 10.1021/cs2001048
[9]	YIN A Y, GUO X Y, DAI W-L, FAN K N. The nature of active copper species in Cu-HMS catalyst for hydrogenation of dimethyl oxalate to ethylene glycol: New insights on the synergetic effect between Cu⁰ and Cu⁺[J]. J Phy Chem C,2009,113(25):11003−11013.
[10]	HUANG X, TESCHNER D, DIMITRAKOPOULOU M, FEDOROV A, FRANK B, KRAEHNERT R, ROSOWSKI F, KAISER H, SCHUNK S, KURETSCHKA C, SCHLOGL R, WILLINGER M G, TRUNSCHKE A. Atomic-scale observation of the metal-promoter interaction in Rh-based syngas-upgrading catalysts[J]. Angew Chem Int Ed,2019,58(26):8709−8713. doi: 10.1002/anie.201902750
[11]	MATEEN M, SHAH K, CHEN Z, CHEN C, LI Y D. Selective hydrogenation of N-heterocyclic compounds over rhodium-copper bimetallic nanocrystals under ambient conditions[J]. Nano Res,2019,12(7):1631−1634. doi: 10.1007/s12274-019-2411-y
[12]	KRISHNAMURTHY R, CHUANG S S, GHOSAL K. Carbon monoxide adsorption and hydrogenation on Cu-Rh/SiO₂ catalysts[J]. Appl Catal A: Gen,1994,114(1):109−125. doi: 10.1016/0926-860X(94)85111-5
[13]	ZHAO Y H, YANG M M, SUN D P, SU H Y, SUN K J, MA X F, BAO X H, LI W-X. Rh-decorated cu alloy catalyst for improved C₂ oxygenate formation from syngas[J]. J Phys Chem C,2011,115(37):18247−18256. doi: 10.1021/jp204961g
[14]	WEISZ P B. Polyfunctional heterogeneous catalysis[J]. Adv Catal,1962,13:137−190.
[15]	KIM J, KIM W, SEO Y, KIM J-C, RYOO R. n-Heptane hydroisomerization over Pt/MFI zeolite nanosheets: Effects of zeolite crystal thickness and platinum location[J]. J Catal,2013,301:187−197. doi: 10.1016/j.jcat.2013.02.015
[16]	BATALHA N, PINARD L, BOUCHY C, GUILLON E, GUISNET M. n-Hexadecane hydroisomerization over Pt-HBEA catalysts. Quantification and effect of the intimacy between metal and protonic sites[J]. J Catal,2013,307:122−131. doi: 10.1016/j.jcat.2013.07.014
[17]	ZECEVIC J, VANBUTSELE G, DE JONG K P, MARTENS J A. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons[J]. Nature,2015,528(7581):245−248. doi: 10.1038/nature16173
[18]	CHENG K, ZHOU W, KANG J C, HE S, SHI S L, ZHANG Q H, PAN Y, WEN W, WANG Y. Bifunctional catalysts for one-step conversion of syngas into aromatics with excellent selectivity and stability[J]. Chem,2017,3(2):334−347. doi: 10.1016/j.chempr.2017.05.007
[19]	CHENG K, GU B, LIU X L, KANG J C, ZHANG Q H, WANG Y. Direct and highly selective conversion of synthesis gas into lower olefins: design of a bifunctional catalyst combining methanol synthesis and carbon-carbon coupling[J]. Angew Chem Int Ed,2016,55(15):4725−4728.
[20]	KANG J C, HE S, ZHOU W, SHEN Z, LI Y Y, CHEN M S, ZHANG Q H, WANG Y. Single-pass transformation of syngas into ethanol with high selectivity by triple tandem catalysis[J]. Nat Commun,2020,11(1):1−11. doi: 10.1038/s41467-019-13993-7
[21]	HANNAGAN R T, PATEL D A, CRAMER L A, SCHILLING A C, RYAN P T P, LARSON A M, ÇINAR V, WANG Y C, BALEMA T A, SYKES E C H. Combining STM, RAIRS and TPD to decipher the dispersion and interactions between active sites in RhCu single-atom alloys[J]. ChemCatChem,2019,12(2):488−493.
[22]	GONZALEZ S, SOUSA C, ILLAS F. Features and catalytic properties of RhCu: A review[J]. Int J Mod Phy B,2010,24(25/26):5128−5138.
[23]	LI C, LIU J, GAO W, ZHAO Y, WEI M. Ce-promoted Rh/TiO₂ heterogeneous catalysts towards ethanol production from syngas[J]. Catal Lett,2013,143(11):1247−1254. doi: 10.1007/s10562-013-1100-9
[24]	WANG B, CUI Y Y, WEN C, CHEN X, DONG Y, DAI W L. Role of copper content and calcination temperature in the structural evolution and catalytic performance of Cu/P25 catalysts in the selective hydrogenation of dimethyl oxalate[J]. Appl Catal A: Gen,2016,509:66−74. doi: 10.1016/j.apcata.2015.10.022
[25]	KACIMI S, BARBIER, J. , TAHA, R. Oxygen storage capacity of promoted Rh/CeC₂ catalysts. Exceptional behavior of RhCu/CeO₂[J]. Catal Lett,1993,22:343−350. doi: 10.1007/BF00807243
[26]	EGBEBI A, SCHWARTZ V, OVERBURY S H, SPIVEY J J. Effect of Li promoter on titania-supported Rh catalyst for ethanol formation from CO hydrogenation[J]. Cataly Today,2010,149(1-2):91−97. doi: 10.1016/j.cattod.2009.07.104
[27]	JIANG B, KANI K, IQBAL M, ABE H, KIMURA T, HOSSAIN M S A, ANJANEYULU O, HENZIE J, YAMAUCHI Y. Mesoporous bimetallic RhCu alloy nanospheres using a sophisticated soft-templating strategy[J]. Chem Mater,2018,30(2):428−435. doi: 10.1021/acs.chemmater.7b04307
[28]	GONG J L, YUE H R, ZHAO Y J, ZHAO S, ZHAO L, LV J, WANG S P, MA X B. Synthesis of ethanol via syngas on Cu/SiO₂ catalysts with balanced Cu⁰-Cu⁺ sites[J]. J Am Chem Soc,2012,134(34):13922−13925. doi: 10.1021/ja3034153
[29]	YIN A, GUO X, DAI W-L, FAN K. The nature of active copper species in Cu-HMS catalyst for hydrogenation of dimethyl oxalate to ethylene glycol: New insights on the synergetic effect between Cu⁰ and Cu⁺[J]. J Phys Chem C,2009,113(25):11003−11013. doi: 10.1021/jp902688b
[30]	LIU W C, MELAET G, RALSTON W T, ALAYOGLU S, HOROWITZ Y, YE R, HURLBURT T, MAO B, CRUMLIN E, SALMERON M, SOMORJAI G A. Co-Rh nanoparticles for the hydrogenation of carbon monoxide: Catalytic performance towards alcohol production and ambient pressure X-Ray photoelectron spectroscopy study[J]. Catal Lett,2016,146(8):1574−1580. doi: 10.1007/s10562-016-1782-x
[31]	ZHENG X L, LIN H Q, ZHENG J W, DUAN X P, YUAN Y Z. Lanthanum oxide-modified Cu/SiO₂ as a high-performance catalyst for chemoselective hydrogenation of dimethyl oxalate to ethylene glycol[J]. ACS Catal,2013,3(12):2738−2749. doi: 10.1021/cs400574v
[32]	HADJIIVANOV K, KNÖZINGER H. FTIR study of CO and NO adsorption and coadsorption on a Cu/SiO₂ catalyst: Probing the oxidation state of copper[J]. Phys Chem Chem Phys,2001,3(6):1132−1137. doi: 10.1039/b009649k
[33]	YANG A C, GARL C W. Infrared studies of carbon monoxide chemisorbed on rhodium[J]. J Phys Chem,1957,61(11):1504−1512. doi: 10.1021/j150557a013
[34]	JIANG D H, DING Y J, PAN Z D, CHEN W M, LUO H Y. CO Hydrogenation to C₂-oxygenates over Rh-Mn-Li/SiO₂ catalyst: Effects of support pretreatment with nC₁–C₅alcohols[J]. Catal Lett,2008,121(3):241−246.
[35]	FORCE C, BELZUNEGUI J, SANZ J, MARTıNEZ-ARIAS A, SORIA J. Influence of precursor salt on metal particle formation in Rh/CeO₂ catalysts[J]. J Catal,2001,197(1):192−199. doi: 10.1006/jcat.2000.3067
[36]	ANDERSON J A, ROCHESTER C H, WANG Z. IR study of CO adsorption on Cu–Rh/SiO₂ catalysts, coked by reaction with methane[J]. J Mol Catal A: Chem,1999,139(2/3):285−303. doi: 10.1016/S1381-1169(98)00206-4
[37]	QI J, CHRISTOPHER P. Atomically dispersed Rh active sites on oxide supports with controlled acidity for gas-phase halide-free methanol carbonylation to acetic acid[J]. Ind Eng Chem Res,2019,58(28):12632−12641. doi: 10.1021/acs.iecr.9b02289