STUDY IN NEW DEHYDROGENATION USING A HYDROGEN-PERMEABLE MEMBRANE REACTOR

采用透氢膜反应器，在623 ~ 723K的较低温度范围内进行异丁烷脱氢制异丁烯。al_2o_3负载Pt催化剂在常规流动反应器中表现出比商用Cr_2O_3-Al_2O_3催化剂更高的活性。然而，在膜反应器中，Pt催化剂的异丁烯产率低于Cr_2O_3-Al_2O_3催化剂，尽管这两种催化剂的异丁烯产率都比在常规反应器中可以达到的热力学平衡产率高，这是由于平衡向产物侧的转移。结果表明，由于碳质物质的沉积，铂催化剂在膜反应器中劣化速度更快。另一方面，在膜反应器中，由于去除了反应侧产生的氢，抑制了氢异构化和氢解等不良副反应，从而使异丁烯具有高选择性。在Pt/Al_2O_3中添加Sn可有效提高膜反应器中脱氢的催化活性。

The dehydrogenation of isobutane to isobutene was conducted in a comparatively low temperature range between 623 and 723K using a hydrogen permeable membrane reactor. Al_2O_3-supported Pt catalyst exhibited high activity compared with a commercial Cr_2O_3-Al_2O_3 catalyst in a conventional flow reactor. In the membrane reactor, however, the Pt catalyst gave a lower yield of isobutene than the Cr_2O_3-Al_2O_3 catalyst, although the isobutene yields on both of these catalysts were high compared with thermodynamic equilibrium ones attainable in a conventional reactor, due to the shift of equilibrium toward the product side. It was shown that the Pt catalyst was more rapidly deteriorated in the membrane reactor, due to deposition of carbonaceous matters. On the other hand, undesirable side reactions such as hydroisomerization and hydrogenolysis were suppressed in the membrane reactor due to the removal of produced hydrogen from the reaction side, leading to high selectivity for isobutene. The addition of Sn to Pt/Al_2O_3 was effective to enhance the catalytic activity for dehydrogenation in the membrane reactor.