选取无定形硅铝(ASA)作为生物质热裂解气齐聚反应催化剂,分析了齐聚反应前后ASA的织构性质、酸性和积碳行为的变化规律,并在固定床反应器中评价了ASA在不同反应条件(100-320℃,2.0-4.0MPa)下的齐聚反应性能.结果表明,在不同齐聚反应条件下ASA均有不同程度的酸性损失和积碳,L酸位量损失随着温度升高呈现先降低后增加的趋势,在280℃达到最低;压力的升高则有利于降低L酸位量的损失.催化剂积碳量变化与L酸位量变化趋势一致.在反应过程中,低碳烯烃转化率和汽油段产物收率随着温度和压力的升高逐渐增大,在4.0 MPa,280℃反应条件下达到最优,其乙烯、丙烯和丁烯的反应转化率分别为19.2%,37.3%和58.7%,汽油段产物收率(摩尔分数)为22.9%,C5-+的烯烃类选择性可达73.5%.
The oligomerization performances of biomass cracking gas over amorphous silica-alumina( ASA)were investigated in a fixed bed in the region of 100—320 ℃ and 2. 0—4. 0 MPa. NH3-TPD,Py-IR,TG,SEM,BET and XRD were used to characterize the surface structures,acidity properties and carbon deposition of catalysts. The results showed that there were different degrees of acid amount loss and carbon deposition for ASA during oligomerization under different reaction conditions. The loss of Lewis acid amount decreased gradually with increasing temperature,and reached the minimum at 280 ℃,and then begun to increase with continual increase of temperature. The increase of pressure is beneficial to reduce the Lewis acid loss. The change trend of carbon deposition was consistent with that of Lewis acid loss. During oligomerization,the conversion of light olefins and yield of gasoline range products increased gradually with the increase of temperature and pressure,and reached the maximum at 4. 0 MPa and 280 ℃. The conversions of ethylene,propylene and butylene reached 19. 2%,37. 3% and 58. 7%,respectively. The yield of gasoline range product reached 22. 9%( molar fraction),and the selectivity of C5+olefins reached 73. 5%.