电场辅助钌基催化剂低温分解氨制氢反应

Electric field-assisted low-temperature decomposition of ammonia to hydrogen over ruthenium-based catalysts

摘要:

为提升Ru/CeO₂催化剂在低温下分解氨制氢效率,以硝酸铈铵和草酸铵一水合物为原料,采用草酸盐沉淀法合成CeO₂载体,以乙酰丙酮钌为原料,采用预浸渍法将Ru负载到CeO₂上,合成Ru/CeO₂催化剂,并对催化剂反应床外加电场。分别在外加电场条件和非电场条件下用气相色谱仪测试氨分解性能,并采用XRD,XPS,TEM、程序升温还原和程序升温吸脱附对Ru/CeO₂和电场处理后的Ru/CeO₂进行理化特征表征。电场条件下,在400℃、纯氨体积空速(GHSV)为3000 mL?g_cat?1^?h_?1^{时获得高达}98%的氨分解率,Ru/CeO₂催化剂分解氨的表观活化能降低57.3KJ/mol。催化剂理化特征分析表明,电场处理增加了Ru的碱性位点和酸性位点,增强了RuO₂与CeO₂之间的相互作用,改善了CeO₂与Ru活性位点之间的电子转移。通过电场与高活性的Ru/CeO₂催化剂相结合,实现了经济高效制氢。关键词：电场；活化能；纯氨分解；酸碱度；氧空位

Abstract:

In order to enhance the efficiency of Ru/CeO₂ catalysts for ammonia decomposition and hydrogen production at low temperatures, CeO₂ carriers were synthesized from ceric ammonium nitrate and ammonium oxalate monohydrate by oxalate precipitation, and Ru/CeO₂ catalysts were synthesized from ruthenium acetylacetonate by pre-impregnation method with Ru loaded onto CeO₂, and the catalysts" reaction beds were externally applied with an electric field. The ammonia decomposition performance was tested by gas chromatography under applied electric field conditions and non-electric field conditions, respectively, and the physicochemical characterization of Ru/CeO₂ and Ru/CeO₂ after electric field treatment was carried out by XRD, XPS, TEM, programmed elevated-temperature reduction and programmed elevated-temperature adsorption and desorption. Under electric field conditions, up to 98% ammonia decomposition was obtained at 400 ℃ with a pure ammonia volumetric space velocity (GHSV) of 3000 mL?gcat_-1^?h^_-1, and the apparent activation energy for ammonia decomposition of the Ru/CeO₂ catalyst was reduced by 57.3 KJ/mol. The physicochemical characterization of the catalysts showed that the electric field treatment increased the number of the basic and acidic sites of Ru, enhanced the interaction between RuO₂ and CeO₂, and improved the electron transfer between CeO₂ and Ru active sites. By combining the electric field with the highly active Ru/CeO₂ catalyst, the economic and efficient hydrogen production was realized.