碳四烯烃制丙烯催化剂的稳定性

Stability of the catalyst for C_4 alkenes to propylene

以超细氧化硅为载体,高硅铝比的ZSM-5分子筛为活性组分,挤条制成催化剂,用氧化钙和氧化镧的前驱体化合物改性,分别在800℃焙烧和600℃水蒸汽的条件下进行处理,在500℃、0.1MPa、水与碳四质量比0.2和碳四空速3 h^(-1)的条件下,对催化剂性能进行评价。对成型、改性、水热处理和再生后的催化剂采用BET、NH_3-TPD和Py-IR方法进行表征。结果表明,催化剂长时间在800℃焙烧和600℃水蒸汽条件下处理后活性降低,催化剂活性与表面L酸量和B酸量变化有关。

The catalyst for catalytic cracking of C4 alkenes to propylene was prepared using ultra-fine silicon oxide as the carrier and ZSM-5 molecular sieve with high SiO2/Al2O3 molar ratio as the active component. The precursors of CaO and La2O3 were used to adjust the acidic properties of the catalyst. The catalysts co-modified by CaO and La2O3 were pretreated at 800 ℃ under the protection of inert gas for 48 h or at 600℃ with water vapor for 24 h. The properties of the catalysts were investigated under the the reaction condition as follows： 500℃,0. 1 MPa,w（H2O）： w（C4= ） =0. 2, C4 space velocity 3 h-1 ,and continuous operation for 25 days. The as-prepared catalysts were characterized by BET, NH3-TPD and Py-IR. The results showed that the activity of the catalysts were decreased after long time treatment at 800 ℃ or 600℃ with water vapor. The characterization results indicated that the catalytic activity of the catalysts was related to the contents of Lewis acid and Bronsted acid on its surface.