助剂对Ni-Al合金和Raney-Ni催化剂结构及1,4-丁烯二醇加氢性能的影响

采用等体积浸渍法将助剂(MgO、CuO、Co2O3)引入商品Ni-Al合金粉,经10%(w/w)NaOH溶液浸取制备Raney-Ni催化剂。通过能量色散X射线(EDX)、X射线衍射(XRD)、N2吸附-脱附测试、透射电镜(TEM)、NH3程序升温脱附(NH3-TPD)、X射线光电子能谱(XPS)等方法表征和评价实验,考察了金属助剂对Ni-Al合金粉及Raney-Ni催化剂元素组成、晶相结构、孔结构特征、表面形貌、表面酸碱性的影响。表征分析显示,不同助剂催化剂的元素含量、比表面积及表面形貌均表现出明显的差异。其中,添加助剂Cu的催化剂表面检测到较多的活性组分Ni,接近90%(w/w),该催化剂平均孔径最小(3.87 nm)、活性组分Ni颗粒分散性好。评价结果表明,该催化剂具有较佳的加氢性能,其1,4-丁烯二醇(BED)转化率为100%,1,4-丁二醇(BDO)选择性和收率分别为59.62%和59.62%,这与该催化剂较大的活性组分Ni负载量、酸强度和适中的酸量及存在的Cu对Ni分散性的提高进一步防止了Ni的严重烧结(即"限域效应")等有较大关联。

Effect of Promoter on the Ni-Al Alloy & the Corresponding Raney-Ni Catalyst and Hydrogenation Performance of 1,4-Butylenediol

Three promoters (MgO, CuO, Co₂O₃) were introduced individually into the commercial Ni-Al alloy powder by impregnation method, and the modified alloys were leached by 10%(w/w) NaOH solution to prepare Raney-Ni catalysts. Effect of promoter on the elemental composition, crystal structure, pore structure, surface morphology and surface acidity of the Ni-Al alloy and the corresponding Raney-Ni catalyst was investigated by energy dispersive X-ray (EDX), X-ray diffraction (XRD), N₂ adsorption-desorption, transmission electron microscope (TEM), NH₃ temperature programmed desorption (NH₃-TPD) and X-ray photoelectron spectroscopy (XPS) methods. Results showed that the element content, specific surface area and surface morphology of the catalyst modified by different promoter proposed significant difference. Large amount of Ni- the active component on the Cu-modified catalyst was detected with the content of about 90%(w/w), showing excellent dispersion, and the catalyst presented small average pore size (3.87 nm). Evaluation results showed that the catalyst displayed well hydrogenation performance, with 1,4-butenediol (BED) conversion of 100%, both 1,4-butanediol (BDO) selectivity and yield of 59.62%, which was related to the high Ni content, the moderate amount of acid sites and the small Cu crystal for improving Ni dispersion without serious sintering by the "confinement effect".