热处理对Co@MFI催化剂丙烷脱氢性能的影响

Effect of High-temperature Pretreatment on Catalytic Propane Dehydrogenation over Co@MFI Catalysts

Co基催化剂因其低成本和环境友好而有望成为丙烷无氧脱氢制丙烯的工业催化剂,但Co物种在高温下易积碳失活、低温下活性较低等不足限制了Co基催化剂在丙烷脱氢领域的应用。作者以Co(NO_(3))_(2)为Co源、正硅酸四乙酯(TEOS)为Si源,通过一锅水热法合成了Co@MFI催化剂,并用于丙烷无氧脱氢制丙烯。实验结果表明,惰性气氛中高温处理可以显著提高Co@MFI催化剂的初始活性。结合XRD、XPS、H_(2)-TPR等表征结果表明高度分散、难还原的Co(Ⅱ)是脱氢的活性物种,高温惰性气体处理可以通过分子筛表面脱羟基效应除去分子筛表面水,从而增加活性位点。本研究为提高分子筛型催化剂低温丙烷脱氢活性提供了一种有效的方法。

Cobalt based catalysts are promising for propane dehydrogenation to propylene owing to their low price and environmentally friendly.However,their application in propane dehydrogenation is limited due to the deactivation caused by carbon deposition at high temperature and the low catalytic activity exhibited at low temperatures.In this work,Co@MFI Catalysts were synthesized by one pot hydrothermal method using Co(NO_(3))_(2) as the Cobalt source and tetraethyl orthosilicate(TEOS)as the silicon source,and were used for propane nonoxidative dehydrogenation to propylene.The experimental results proved that high-temperature pretreatment in an inert atmosphere can significantly improve initial activity of the Co@MFI catalysts.Characterization results of XRD,XPS,H_(2)-TPR showed that highly dispersed and difficult to reduce Co(Ⅱ)was an active species for dehydrogenation.High temperature inert gas pretreatment can remove surface water via the surface dehydroxylation effect of the catalyst,thereby increase the number of active sites.The research results provide an effective method for improving the low-temperature propane dehydrogenation activity of the catalysts.