碳纳米管负载合成气制低碳醇Co-Mo-K硫化物基催化剂  

Co-Mo-K Sulfide-based Catalyst Supported by Carbon Nanotubes for Higher Alcohol Synthesis from Syngas

作　　者：马晓明[1] 武小满[1] 林国栋[1] 张鸿斌[1] 

机构地区：[1]厦门大学化学化工学院固体表面物理化学国家重点实验室,福建厦门361005

出　　处：《厦门大学学报（自然科学版）》2006年第6期797-804,共8页Journal of Xiamen University：Natural Science

基　　金：国家973项目(2005CB221400);国家自然科学基金项目(20473063;20590364)共同资助

摘　　要：用自行制备的多壁碳纳米管(CNTs)作为载体,制备一类负载型CNTs促进Co-Mo-K硫化物基催化剂,x%CoiMojKk/CNTs(x%为质量百分数).实验发现,在2.0 MPa、593 K、V(CO):V(H2):V(N2)=45:45:10、GHSV=2 400mLSTP.h-1.g-cat.-1的反应条件下,在11.6%Co1Mo1K0.6/CNTs催化剂上,所观测低碳醇合成的比反应速率达到0.77μmol-CO.s-1.(mmol-Mo)-1,是AC和-γAl2O3分别负载各自最佳Co-Mo-K摩尔组成及相应负载量催化剂(50.3%Co1Mo1K0.8/AC和26.1%Co1Mo1K0.8/γ-Al2O3)上这个值(分别为0.23和0.27μmol-CO.s-1.(mmol-Mo)-1)的3.35和2.85倍.对比研究显示,用CNTs代替常规载体AC和-γAl2O3并不引起所负载Co1Mo1K0.6硫化物催化剂上低碳醇合成反应的表观活化能发生明显变化.与AC或-γAl2O3负载的参比体系相比,CNTs负载的催化剂更易于在较低温度下还原活化,并促使工作态催化剂表面催化活性Mo物种(Mo4+)在总Mo量中所占份额明显提高;在另一方面,CNTs负载的催化剂展现出对H2更强的吸附活化能力,有助于在工作态催化剂表面营造较高稳态浓度吸附氢的表面氛围,于是提高了表面加氢反应的速率;这些因素对低碳醇合成反应活性的提高都有重要贡献.With home-made multi-walled carbon nanotubes（MWCNTs,simplified as CNTs）as support, CNT-supported Co-Mo-K sulfide catalysts,denoted as x% （mass percentage） CoiMojKk/CNTs, were prepared. Their catalytic performance for higher alcohol synthesis（HAS）from syngas was evaluated,and compared with the reference system supported by AC or γ-Al2O3. Over the 11.6% Co1Mo1K0.6/CNTs catalyst under reaction condition of 2.0 MPa,593 K,V（CO） ： V（H2） ： V（N3）=45 ： 45 ： 10 and GHSV=2 400 mLSTP·h^-1 · gcsL^-1 ,the specific reaction rate of HAS reached 0.77 μmol-CO · s^-1 · （mmol-Mo）^-1 ,which was 3.35 and 2.85 times as high as that [0.23 and 0.27 μmol-CO · s^-1 · （mmol-Mo）^-1] of the reference systems supported by AC and γ-Al2O3 with the respective optimal molar composition and loading amount of CoiMojKk, S0. 3 % Co1Mo1K0.8 / AC and 26. 1% Co1Mo1K0.8/γ-Al2O3 ,respectively. It was experimentally found that using the CNTs in place of AC or γ-Al2O3 as support of the catalyst caused little change in the apparent activation energy for the HAS reaction, but led to a significant increase in concentration of catalytically active Mo-species（Mo^4＋ ）at the surface of the functioning catalyst. On the other hand, H2-TPD measurements revealed that the CNT- supported catalyst could reversibly adsorb a greater amount of hydrogen under atmospheric pressure at temperatures ranging from room temperature to ～673 K. This unique feature would help to generate microenvironments with higher stationary-state concentration of active hydrogen-adspecies at the surface of the functioning catalyst. Both factors mentioned above were favorable to increasing the rate of HAS reactions.

关 键 词：多壁碳纳米管 碳纳米管负载CoMoK硫化物基催化剂 低碳醇合成 合成气催化转化 

分 类 号：O643[理学—物理化学]