摘要
用溶胶 凝胶法合成了K Co Mo催化剂 .样品经不同温度还原后 ,用于低碳醇的合成 .XRD和HRTEM结果表明 ,样品是超细粒子 ,粒子尺寸为 2～ 5nm .考察了催化剂的还原温度和反应条件对催化剂性能的影响 .实验结果表明 ,还原温度对催化剂的活性有较大的影响 ,最佳还原温度为 5 0 0℃ .最佳反应温度范围为 310～ 330℃ .升高压力和空速可以提高醇的收率和选择性 .在空速 14 4 0 0h-1,压力 6 0MPa和温度 310℃的条件下 ,醇的选择性为 5 5 8% ,收率为 5 2 0 0g/ (kg·h) ,MeOH/C2 + OH为 0 2 7.催化剂稳定性良好 ,在 2 0 0h的寿命实验中 ,活性基本不变 .与文献中催化剂相比 ,超细K Co Mo催化剂对合成醇具有较高的活性和选择性 ,尤其是对C2 +
The mixed alcohol synthesis is an important reaction in C1 chemistry. Mol ybdenum-based catalysts modified with alkali and cobalt promoters have attract ed special interest because of their higher yield of the mixed alcohol and highe r C 2+ alcohol selectivity. In this work, the K-Co-Mo catalyst ( n(K) / n(Mo) =0 2, n(Co) / n(Mo) =0 5) was prepared by sol-gel method. The structure of the cata lyst sample was characterized by XRD and HRTEM, and the results revealed that the catalyst is of ultra-fine particles. The influence of the catalyst reducti on temperature and the reaction conditions on the catalytic performance was inve stigated, and the catalyst life and stability was also measured. The reduction t emperature was a very important factor affecting the catalytic performance and t he optimum reduction temperature was 500 ℃. At 500 ℃, the selectivity and the STY of mixed alcohol reached their maxima, and the ratio of MeOH/ C 2+ OH decreased to a minimum. There existed an optimum reaction temperature range, w hich was from 310 to 330 ℃. In this temperature range, the STY of the mixed a lcohol enhanced with the temperature, whereas it decreased quickly when the temp erature exceeded 330 ℃, and MeOH/ C 2+ OH reached the minimum at 330 ℃ . The percent of water in the liquid product also increased when the reaction te mperature elevated. The selectivity and STY of mixed alcohol increased with syng as pressure and feed gas space velocity. Under the conditions of 310 ℃, 6 0 MP a and 14?400 h -1 , the STY of mixed alcohol was 520 0 g/(kg·h) , the selectivity for mixed alcohol was 55 8% and the ratio of MeOH/ C 2+ OH was 0 27. The performance of the catalyst for mixed alcohol synthesis was st able in the reaction for 200 h. In comparison with other catalysts from literatu re and patents, the ultra-fine K-Co-Mo catalyst showed higher selectivity and STY toward mixed alcohol synthesis, especially to C 2+ OH formation.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2003年第11期826-830,共5页
关键词
溶胶—凝胶法
钾
钴
钼
超细催化剂
还原温度
低碳醇
sol-gel method, potassium, cobalt, molybdenum, ultra-fine catalyst, reduction temperature, mixed alcohol
