磷对Re基催化剂上丁烯自歧化反应性能的影响

采用等体积浸渍法制备了不同磷含量的Re2O7/γ-Al2O3催化剂,同时以混合丁烯为原料,在固定床反应器上考察了该催化剂在混合丁烯自歧化反应中的催化性能,并采用XRD、NH3-TPD、H2-TPR、N2吸附和TG等方法对催化剂进行了表征。实验结果表明,磷的引入增加了催化剂的酸量和不易还原Re物种的含量,有利于提高催化剂在丁烯自歧化反应中的稳定性。当磷含量为8%(相对于载体质量)时,催化剂的比表面积下降明显,反应稳定性降低。以5%P-1%Re2O7/γ-Al2O33(磷含量5%(w),Re2O7负载量1%(w))为催化剂,在80℃、1.0 MPa、n(1-丁烯)∶n(2-丁烯)=3、混合丁烯WHSV=1.2 h-1、催化剂用量4.9 g的条件下,混合丁烯自歧化反应连续进行55 h,丁烯转化率达到50%以上,丙烯收率达到12%以上。

Self-metathesis of 1-butene to ethene and hexene over molybdenum-based heterogeneous catalysts

A novel route involving self‐metathesis of1‐butene under mild conditions that gave high yields ofethene and hexene was proposed.The results of thermodynamic analysis revealed that the Gibbsenergy of the target Metathesis I reaction(1‐butene?ethene+3‐hexene)was much higher thanthat of the main side Metathesis II(1‐butene+2‐butene?propene+2‐pentene).Suppression of1‐butene double‐bond isomerization was the key step to increase the selectivity for the target olefinin the reaction network.The relationship between the catalytic performance and support nature was investigated in detail.On basis of H2‐TPR,UV‐Vis spectra and HRTEM results,an alumina(Al2O3)support with large surface area was beneficial for the dispersion of molybdenum(Mo)species.Both suitable acidity and sufficient Mo dispersion were important to selectively promote the self‐metathesis reaction of1‐butene.On the optimal6Mo/Al2O3catalyst,1‐butene conversion reached47%and ethene selectivity was as high as42%on the premise of good catalytic stability(80°C,1.0MPa,3h?1).?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.