脱铝USY催化剂上柠檬酸三丁酯的合成

Synthesis of tributyl citrate by dealuminium USY zeolite catalyst

对超稳Y沸石(USY)进行水蒸气和硝酸铵水溶液脱铝,并采用过量浸渍法制备脱铝USY负载磷钨酸(PW)催化剂,使用氨程序升温脱附(NH3-TPD)技术表征其酸性质,并在柠檬酸与正丁醇的酯化反应中考察其催化性能。结果表明:催化剂的酸量和酸强度与USY脱铝程度相关,水蒸气脱铝后的USY1具有较大酸量和适宜的酸强度。USY1催化剂具有最大的柠檬酸转化率(97.3%),柠檬酸正三丁酯的选择性为98.8%,适宜反应条件为反应温度110℃,反应时间90 min;反应4次后柠檬酸的转化率保持在80%以上,产品选择性高于98%。

Catalysts were made by dealuminumed ultrastable Y-type zeolite （USY） treated with water vapour and ammonium nitrate aqueous solution and then 12-tungstophosphoric acid （PW） immobilized. The acid properties of catalysts were identified by ammonia program temperature desorption （ NH3-TPD） techniques. The results showed that the acid amount and the acid site strength of sample were related with the dealuminum degree of USY. USY1 kept the more acid amount and the medium acid site strength after vapour dealuminum. Catalytic performances of catalyst samples for esterification of citric acid and n-butyl alcohol were investigated. Experimental results showed that under the suitable reaction conditions of reaction temperature 110 ℃ and balanced time 90 rain, the conversion of citric acid was 97.3%, and the selectivity of tributyl citrate was higher than 98.8%. After catalyst recycle four times, the conversion of citric acid kept more than 80% and the selectivity of tributyl citrate was above 98%.