Production of H_2 from Decomposition of CH_3OH over CNT-supported/promoted Cu-Cr Catalyst
- 化学化工－已发表论文 
[中文摘要]用自行制备的碳纳米管(CNTs)作为载体,研制出一类高活性CNTs负载/促进甲醇分解制氢Cu Cr/CNTs催化剂.实验结果显示,在0.1MPa,503K,n(CH3OH) n(Ar)=2 1,GHSV=3600h-1的反应条件下,27%Cu10Cr1/CNTs催化剂上H2的时空产率达133mmol H2h-1(g catal.)-1,是AC、SiO2和γ Al2O3负载相应参比催化剂(分别为:111、73.5、60.9mmol H2h-1(g catal.)-1)的1.20、1.81和2.18倍.实验表征研究揭示,碳纳米管载体促使催化剂活性Cu表面积大为增加,并诱使Cu Cr催化活性位上甲醇分子解离下来的吸附H物种向碳纳米管载体"溢流"、疏散、随后偶联成H2(a)脱附,于是降低了副产物甲醛、甲酸甲酯的生成机率,有利于提高甲醇深度脱氢、生成H2和CO的选择性.[英文摘要]With a kind of multi-walled carbon nanotubes (CNTs) synthesized catalytically inhouse and the nitrates of the corresponding metallic components, highly active CNT-supported and promoted catalysts, wt%CuiCrj/CNTs, were prepared by an incipient wetness method, and their catalytic performance for production of H2 from decomposition of CH3OH was investigated and compared with the corresponding those supported by AC, SiO2 and γ-Al2O3. It was experimentally found that the support could significantly affect the catalyst activity for methanol decomposition.Over a 27%Cu10Cr1/CNTs catalyst,space-time-yield of H2 reached 133m molH2h-1(g-catal.)-1 under reaction condition of 0.1 MPa,503 K,n(CH3OH) Ln(Ar)=2L1,GHSV=3600h-1,which was 1.20,1.81 and 2.18 times as high as those of the reference systems supported by AC,SiO2 and γ-Al2O3 at the same reaction condition,respectively. The nature of promoter action by the CNTs was discussed together with the results of characterization study of the CN T-carrier and the CNT-supported catalysts by TEM, XRD, TPR,TPD and Cu exposed area.The results indicated that the CN Ts served not only as a carrier , but also as an excellent dispersant for Cu-Cr2O3 components,which led to a significant increase of the Cuexposed area,generating more catalytically active Cu2sites at the catalyst surface for methanol decomposition. On the other hand, the CNTs could serve as an excellent promoter for”hydrogen spill2over”from the catalytically active sites of Cu-Cr to CNT-carrier,which would be conducive to scattering hydrogen-adspecies produced from dehydrogenation of methanol molecules at Cu-Cr sites and transferring them to the CNT carrier,followed by the coupling and desorption,thus favorable to reducing the probability of formation of the by-products, formaldehyde and methylformate, and enhancing the selectivity of deep dehydrogenation of methanol to form H2 and CO.