MgO对NiMgAlCa复合催化剂结构及吸附强化制氢性能的影响

Influence of MgO on the structure and adsorption-enhanced hydrogenproduction performance of NiMgAlCa composite catalyst

CO_(2)吸附强化甲烷水蒸气重整制氢工艺大规模应用的关键技术之一是开发一种具有高催化和吸附能力的复合催化剂。采用共沉淀法制备了系列不同MgO添加量的NiMgAlCa复合催化剂,探究了MgO添加量对NiMgAlCa复合催化剂结构及CO_(2)吸附强化甲烷水蒸气重整制氢性能的影响。研究发现,少量MgO的添加可显著提高NiMgAlCa复合催化剂的活性。在CO_(2)吸附强化CH_(4)/H_(2)O重整反应过程中,MgO添加质量分数为1%的复合催化剂可获得高体积分数的H_(2)(98.7%),CH_(4)转化率达96.5%。制氢性能的提高归因于MgO的添加,赋予了NiMgAlCa复合催化剂中活性组分Ni和载体之间适当的相互作用,同时复合催化剂高的比表面积(42.5 m^(2)/g)提供了更多的反应活性位点,增强了复合催化剂对CO_(2)的吸附能力;而小粒径的活性组分Ni(13.2 nm)提升了复合催化剂的抗烧结能力,赋予了复合催化剂优越的稳定性。

One of the key technologies for the large-scale application of CO_(2) sorption-enhanced methane steam reforming process for hydrogen production is the development of a composite catalyst with high catalytic and adsorption capacities.In this study,a series of NiMgAlCa composite catalysts with different MgO addition were prepared by co-precipitation method,and the influence of MgO addition on the structure of NiMgAlCa catalyst and its CO_(2) enhanced sorption methane steam reforming performance were investigated.It is found that MgO addition can significantly improve the activity of the NiMgAlCa composite catalysts.In the CO_(2) sorption-enhanced CH_(4)/H_(2)O reforming reaction,the as-synthesized composite catalysts can obtain a high volume fraction of H_(2)(98.7%)and a CH_(4) conversion of 96.5% when MgO addition was 1%.The improved hydrogen production performance was ascribed to the addition of MgO,which endowed the composite catalyst a proper interaction between the active component Ni and the carrier in the NiMgAlCa composite catalyst.Meanwhile the higher specific surface area of the composite catalyst(42.5 m^(2)/g)provids more active sites and enhances CO_(2) sorption.The small Ni particle size(13.2 nm)enhances the anti-sintering capacity of the composite catalyst,endowing the composite catalyst superior stability.