氧化铝煅烧温度对丙烷脱氢催化剂性能的影响

Effect of calcination temperature of alumina on performance of propane dehydrogenation catalysts

针对丙烷脱氢催化剂用氧化铝作为载体时存在的孔结构与表面酸性调节的问题,开发了以海藻酸盐为黏合剂,采用挤出滚圆方法,制备了大孔球形氧化铝颗粒,并以此作为载体负载Pt、Sn活性组分制备了丙烷脱氢催化剂,研究了氧化铝载体煅烧温度对催化剂晶型、孔道结构、表面酸性、H_(2)还原性能与丙烷脱氢性能的影响。实验结果表明:随氧化铝载体煅烧温度提高,氧化铝晶型变化过程为γ→δ→θ→α;催化剂比表面积降低、平均孔径提高、表面弱酸酸性与强酸性位点都有所减少;催化剂的催化活性先升高后下降。采用煅烧温度700℃的氧化铝载体,催化剂抑制Sn还原能力相对最好,且具有最佳的丙烷转化率与丙烯收率,分析原因为其具有适宜的孔道结构与表面酸性。

In view of the adjustment of pore structure and surface acidity for propane dehydrogenation catalyst using alumina as support, the spherical alumina beads with large pores were prepared by extrusion-spheronization method with alginate as binder, and used as the support of catalysts loading Pt and Sn for propane dehydrogenation. The effects of calcination temperature of alumina on crystal phase, pore structure, surface acidity, H_(2) reduction of catalysts and catalytic performance of propane dehydrogenation were investigated. The results show that with the increase of calcination temperature, the crystal phase of catalysts present γ→δ→θ→α;the specific surface area of the catalyst decreases gradually;the average pore size increases;both the strong acidity sites and weak acidity sites of the catalyst are declined;the activity of the catalyst first increases and then decreases. Catalysts with alumina support calcined at 700 ℃ has the relatively stronger ability to inhibit Sn reduction and exhibits the best propane conversion and propylene yield due to its suitable pore structure and surface acidity.