摘要
正丁醛自缩合合成2-乙基-2-己烯醛(辛烯醛)是2-乙基己醇(辛醇)工业生产中实现碳链增长的关键步骤。采用溶胶-凝胶法制备了TiO_2催化剂,使用NH_3-TPD、CO_2-TPD、BET和XRD等手段对TiO_2催化剂酸碱性、织构性质和晶相进行了表征,发现锐钛矿型TiO_2催化剂的表面酸位和碱位数量明显高于金红石型TiO_2。活性评价结果表明,锐钛矿晶型TiO_2催化性能优于金红石晶型TiO_2。以TiO_2凝胶在空气气氛下,于400℃焙烧1 h制备的锐钛矿TiO_2为催化剂,正丁醛自缩合反应适宜的反应条件为:TiO_2用量为15.0%(wt),反应温度180℃,反应时间8 h。在此条件下,正丁醛的转化率可达91.1%,辛烯醛的收率和选择性分别为81.6%和89.6%。TiO_2重复使用7次,催化活性无明显下降。采用GC-MS对反应液进行定性分析,确定了反应副产物,探讨了锐钛矿型和金红石型TiO_2催化性能存在差异的原因,并且构建了锐钛矿型TiO_2催化正丁醛自缩合的反应网络。
n-Butanal self-condensation to synthesize 2-ethyl-2-hexenal is one of the key reactions to achieve carbon-carbon bond extension in industrial production of 2-ethylhexanol. TiO_2 catalysts were prepared by sol-gel methods and characterized by CO_2-TPD, NH_3-TPD, BET and XRD. The results indicate that the numbers of acid sites and base sites on the surface of anatase TiO_2 are significantly higher than that of rutile TiO_2. Activity evaluation results show that the catalytic performance of anatase TiO_2 is superior to that of rutile TiO_2. Anatase TiO_2 catalysts prepared by calcination of TiO_2 gel at 400 for 1℃ h in air were used, and suitable n-butanal self-condensation reaction conditions were obtained as follows： catalyst weight percentage = 15.0%, reaction temperature = 180 ℃and reaction time = 8 h. n-Butanal conversion, 2-ethyl-2-hexenal yield and selectivity are 91.1%, 81.6% and 89.6%, respectively. TiO_2 can be reused for seven times without significant loss of catalytic activity. The by-products existing in the reaction system catalyzed by anatase TiO_2 and rutile TiO_2 are identified by GC-MS, and the difference in the catalytic performance between anatase TiO_2 and rutile TiO_2 is explained. In addition, a possible reaction network for n-butanal self-condensation to 2-ethyl-2-hexenal catalyzed by anatase TiO_2 is established.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2017年第5期1103-1112,共10页
Journal of Chemical Engineering of Chinese Universities
基金
国家自然科学基金(21476058
21506046
21236001)
天津市自然科学基金青年项目(16JCQNJC06100)
关键词
TIO2
晶型
正丁醛
辛烯醛
羟醛缩合
TiO2
crystal form
n-butanal
2-ethyl-2-hexenal
aldol condensation
