摘要
本文研究了气氛和负载金属对SO_4^(2-)/ZxO_2超强酸催化剂正戊烷异构化反应性能的影响。SO_4^(2-)/ZrO_2催化剂在N_2中初活性较高,但稳定性很差,在H_2中活性很低。负载Pt可显著地改善催化剂的活性,选择性和稳定性,负载Ni则使催化剂活性反而降低。催化剂的红外光谱试验结果表明,H_2可使结合在ZrO_2上的SO_4^(2-),部分还原,减少超强酸位,Pt对SO_4^(2-)的还原有阻抑作用,使催化剂表面保留较多的超强酸位,同时又可产生新的强L酸位和B酸位,Ni则使催化剂表面超强酸位减少。将红外光谱结果与反应数据相关联能满意地解释各种催化剂在正戊烷异构化反应中的不同表现。
The effects of different pretreatment and reaction atmospheres and metal loading on the catalytic properties of SO_4^(2-)/ZrO_2 for pentane isomerization reaction were studied. The initial activity of SO_4^(2-)/ZrO_2 in N_2 is quite high, but the catalyst deactivates quickly. In H_2 atmosphere the activity of SO_4^(2-)/ZrO_2 catalyst is markedly lowered. Supporting Pt on SO_4^(2-)/ZrO_2 improves the activity, selectivity and stability of the catalyst significantly, but Ni loading deteriorates the catalyst. IR spectroscopic studies of the catalysts revealed that the SO_4^(2-) on the surface of ZrO_2 may be partially reduced by H_2, and in result the amount of superacidic sites is diminished. Pt loading inhibits the reduction of SO_4^(2-) by H_2, so more superacidic sites are rerained on the surface of the catalyst. In the same time some new strong Lewis and Bronsted acid sites are formed on Pt/ SO_4^(2-)/ ZrO_2. On the contrary the amount of superacidic sites on Ni/SO_4^(2-)/ZrO_2 is even less than that of SO_4^(2-)/ ZrO_2. The behavior of the various catalysts for pentane isomerization reaction is elucidated satisfactorily by correlating the IR spectroscopic results with the reaction data.
基金
国家重大基础研究项目
中国石油化工总公司基金
