热处理白云石-凹凸棒石黏土催化裂解甲苯的性能

Catalytic Cracking Properties of Toluene Calcined Dolomite-Palygorskite Clay

考察了800℃热处理后白云石．凹凸棒石黏土（CDPC）催化裂解甲苯的性能，并对反应前后的催化剂进行表征。结果表明：白云石-凹凸棒石黏土（DPC）热处理后演变为纳米方镁石（MgO）、方钙石（CaO）和斜硅钙石（Ca2SiO4），斜硅钙石继承了凹凸棒石的纳米棒状形貌特征，表明白云石热分解并且发生了硅钙化合反应。在反应温度为800℃时，CDPC的棒状形貌及高的比表面积，使其催化活性优于白云石（DO）和菱镁矿（MA），能彻底将甲苯裂解为H2、CH4等小分子可燃气体。CDPC催化剂在高温（〉700℃）下催化活性更好，反应后催化剂中积碳主要以金属碳化物形式存在，而非石墨型积碳。因此，这种低成本高活性的催化剂比白云石更有利于甲苯催化裂解。

The catalytic performance of dolomite-palygorskite clay （CDPC） catalyst calcined at 800℃ was investigated. The catalyst before and after catalytic reaction was characterized. The results indicate that the dolomite in dolomite-palygorskite clay （DPC） is transformed into CaO, MgO and Ca2SiO4. The produced substance has the original shape of palygorskite, showing the decomposition of dolomite and the occurrence of a calcium silicate reaction. At the reaction temperature of 800℃, the CDPC catalyst shows a greater catalytic activity for the decomposition of toluene than dolomite and magnesite due to its shape of palygorskite and greater surface area, and toluene is mainly decomposed into H2 and CH4. The formation of carbon deposits in the catalyst after the reaction is mainly metal carbides. This catalyst is thus considered as a promising catalyst for catalytic cracking of toluene than dolomite.