载体处理方式对PtSnK/Al_2O_3催化剂异丁烷脱氢性能的影响

Influences of support treatment on the catalytic properties of PtSnK/AI_2O_3 for isobutane dehydrogenation

研究了水热处理和氯化处理氧化铝载体对PtSnK/Al_2O_3催化剂异丁烷脱氢反应的影响,通过低温N_2吸附、XRD、NH_3-TPD、H_2-TPR、CO-TPR等手段考察了水热处理及氯化处理对载体和催化剂试样的孔结构、酸性、晶型和分散度的影响。表征结果显示,氯化处理载体制得的催化剂相比水热处理载体制得的催化剂的异丁烷脱氢活性更好。实验结果表明,水热和氯化处理载体能促进催化剂中活性组分Pt原子的分散,增加脱氢活性位,从而提高异丁烷脱氢反应中异丁烷的转化率,利用氯化处理和水热处理载体制得的催化剂的异丁烷初始转化率分别为61.0%和57.3%,高于未经处理的催化剂的异丁烷初始转化率(51.8%)。载体经处理后增加了催化剂的酸量,造成了异丁烷脱氢反应中异丁烯选择性的降低。

The influences of hydrothermal treatment and chlorination of spherical alumina support on the properties of PtSnK/Al2O3 catalysts for the dehydrogenation of isobutane were studied. The treated supports and the catalysts prepared from the supports were characterized by means of N2 adsorption at low temperature,XRD,NH3-TPD,H2-TPR and CO-TPR. It was showed that the catalyst prepared through the chlorination had higher activity in the dehydrogenation than the catalyst prepared through the hydrothermal treatment. The experimental results indicated that the hydrothermal and chlorination treatment could promote the dispersion of active Pt atoms on the catalysts and increase the dehydrogenation active sites. The initial conversions of isobutane on the untreated catalyst,the catalysts prepared through chlorination and hydrothermal treatment were 51.8%,61.0% and 57.3%,respectively. The acidity of the catalysts increased after the treatments,which led to the decrease of the selectivity to isobutylene in the dehydrogenation.