焙烧温度对1,4-丁烯二醇加氢Cu/Raney-Ni催化剂结构和性能影响

Effect of calcination temperature on the structure and properties of Raney-Ni catalyst for hydrogenation of 1,4-butenediol

在Ni-Al合金粉上浸渍硝酸铜溶液,经不同温度焙烧得到Cu改性Ni-Al合金粉,采用质量分数10%NaOH溶液浸渍上述改性合金粉得Cu/Raney-Ni催化剂。采用EDX、XRD、N 2吸附-脱附、TEM和NH 3-TPD等手段表征了Ni-Al合金粉及相应Raney-Ni催化剂的元素含量、晶体结构、孔结构特征、表面形貌和表面酸碱性,并以1,4-丁烯二醇加氢制1,4-丁二醇为探针反应,考察了焙烧温度对Raney-Ni催化剂加氢性能的影响。表征分析表明,焙烧温度500℃所制备的CRT500催化剂比表面积较大,为64.96 m 2/g;弱酸中心比例较高,达81.2%。结果表明,焙烧温度升高,BED可实现完全转化,BDO选择性和收率均先升高后降低。其中,CRT500加氢性能较好,BED转化率为100.00%,BDO选择性为61.88%。进一步升高焙烧温度,催化剂RCT550和RCT600的BDO选择性和收率反而降低,这是由于高温下催化剂易发生团聚或烧结。结合催化剂表征可知,CRT500具有较好的加氢性能,这与该催化剂具有合适的Ni/Al物质的量比(3.84)、弱酸中心所占比例较大和活性组分Ni分散性好等因素有较大关联。

Ni-Al alloy powder was impregnated with copper nitrate solution,and calcined at different temperatures to obtain Cu-modified Ni-Al alloy powder.The modified alloy powder was leached with a 10%(mass ratio)NaOH solution to obtain the Cu/Raney-Ni catalyst.Elemental composition,crystal structure,pore structure,surface morphology and surface acidity of the Ni-Al alloy powder and corresponding Raney-Ni catalysts were characterized by EDX,XRD,N 2 adsorption-desorption,TEM and NH 3-TPD.The hydrogenation performance of the Raney-Ni catalysts were evaluated using the reaction of 1,4-butenediol(BED)hydrogenation to 1,4-butanediol(BDO)as the probe reaction.The characteristic results showed that the CRT500 catalyst prepared at the calcination temperature of 500℃presented larger specific surface area of 64.96 m 2/g,and the proportion of weak acid sites was high of 81.2%.The reaction results proposed that the reactant of BED could be completely converted,and the selectivity and yield of BDO increased firstly and then decreased as the calcination temperature increased.The CRT500 catalyst presented good hydrogenation performance,with BED conversion of 100.00%,BDO selectivity of 61.88%,while the BDO selectivity of the RCT550 and RCT600 were lower,which might be due to the agglomeration or sintering of the catalyst at higher calcination temperature.The CRT500 catalyst showed excellent hydrogenation performance,which might be attributed to the appropriate molar ratio of Ni/Al(3.84),the large proportion of weak acid sites and good dispersion of active component Ni.