Oxidative Dehydrogenation of Ethane and Propane using Ni-Loaded Catalysts

大多数重要的基本有机化学品乙烯和丙烯都是通过能源消耗和低选择性的轻烃蒸汽裂解生产的。为了开发更具节能和选择性的工艺，对催化氧化脱氢进行了研究。选择了NiO作为催化剂的活性物质，并开发了NiO的载体材料。在600℃的反应温度下，以高表面积的MgO为载体，在5wt %的NiO负载下，乙烷转化率为53%，乙烯选择性为62%。进一步研究发现，利用NiO - ZrO_2作为载体材料，可以将反应温度降低到450℃。对NiO-ZrO_2催化剂的添加剂进行了研究，发现SbOx和P_2O_5对催化活性和对乙烯的选择性有促进作用，在550℃下，添加0.7 wt%的SbOx时，乙烷转化率为35%，乙烯选择性为64%。在Ni0-Zr02催化剂中添加0.52 wt%的P，在450℃下，乙烷转化率为33%，乙烯选择性为62%；提高乙烷/氧比，乙烷转化率为41%，乙烯选择性为65%。结果表明，在不稀释原料的情况下，乙烷对乙烯的选择性最高。该催化剂体系在丙烷氧化脱氢反应中的应用并不成功。将催化剂的制备方法改为在Ni(NO_3)_2和ZrOCl_2的水溶液中加入氨水共沉淀法。该催化剂在400℃丙烷脱氢制丙烯反应中表现出中等活性。采用瞬态响应技术研究了以乙苯为底物的脱氢反应机理。

Most important basic organic chemicals ethylene and propylene are commercially produced by energy consuming and less selective steam cracking of light hydrocarbons. In order to develop more energy saving and selective processes, catalytic oxidative dehydrogenation was investigated.As an active species of the catalyst, NiO was selected, and support material of NiO was exploited. MgO having high surface area was found to be an appropriate support and with 5 wt% loading of NiO on MgO, ethane conversion of 53% and ethylene selectivity of 62% were obtained at the reaction temperature of 600℃.Further studies on exploiting the support material of NiO, ZrO_2 was found to reduce the reaction temperature to 450℃. Additives of NiO-ZrO_2 catalyst were examined and SbOx and P_2O_5 were found to promote the catalytic activity and to increase selectivity to ethylene at 550℃ Ethane conversion of 35% and ethylene selectivity of 64% were obtained with the addition of 0.7 wt% SbOx.Addition of 0.52 wt% of P to Ni0-Zr02 catalyst, afforded ethane conversion of 33% and ethylene selectivity of 62% at 450℃, and an increase in the ratio of ethane/oxygen increased the ethane conversion to 41% with the selectivity to ethylene of 65%. The results are one of the highest selectivity to ethylene from ethane without dilution of the feed.Application of this catalyst system to the oxidative dehydrogenation to propane was not successful. Catalyst preparation was changed to the co-precipitation method using an aqueous solution of Ni(NO_3)_2 and ZrOCl_2 by adding aqueous ammonia. The catalyst exhibited moderate activity in the dehydrogenation of propane to propylene at 400℃.Transient response technique was developed to understand dehydrogenation mechanism using ethylbenzene as a substrate.