氨分解作为一种很有前景的现场制氢技术,关键在于开发出廉价、高性能的催化剂。本研究通过共沉淀法合成系列Ni_(x)Mg_(75–x)Al_(25)类水滑石化合物(HTlc)作为前驱体,经过焙烧和还原处理制备负载型高分散Ni/Mg(Al)O催化剂并用于氨分解制...氨分解作为一种很有前景的现场制氢技术,关键在于开发出廉价、高性能的催化剂。本研究通过共沉淀法合成系列Ni_(x)Mg_(75–x)Al_(25)类水滑石化合物(HTlc)作为前驱体,经过焙烧和还原处理制备负载型高分散Ni/Mg(Al)O催化剂并用于氨分解制氢,采用不同研究手段对样品进行了表征,考察了Ni含量和氨还原对催化性能的影响。结果显示,HTlc前驱体经过焙烧分解形成Mg(Ni,Al)O固溶体,Ni物种与载体之间存在较强的相互作用,经750℃氨还原得到高分散Ni金属纳米颗粒,其平均晶粒尺寸为5.9~7.7 nm。质谱分析表明,氨还原过程中无氮氧化物(NOx)生成,同时750℃氨还原与氢还原催化剂的活性相当,说明氨是一种合适的还原气。催化剂活性随着Ni含量和还原温度升高而增加。其中,750℃氨还原Ni_(20)Mg_(55)Al_(25)催化剂在30000 m L·g^(–1)cat·h^(–1)、600℃下的氨转化率为98%,且在100 h反应过程中转化率保持不变,Ni金属无明显烧结现象,催化剂表现出良好的活性、稳定性和抗烧结性能。展开更多
A sol-gel process catalyzed by oxalic acid was used for the preparation of SiC precursor from raw materials of tetraethyl orthosilicate (TEOS) and sucrose. The precursor thus obtained was homogeneous. Sintered with a ...A sol-gel process catalyzed by oxalic acid was used for the preparation of SiC precursor from raw materials of tetraethyl orthosilicate (TEOS) and sucrose. The precursor thus obtained was homogeneous. Sintered with a certain heating program in an argon flow, the precursor was converted into the high surface area SiC. The high specific surface area silicon carbide was used as catalyst support for ammonia synthesis. The effect of the surface of the support, promoter and the amount of Ru on the catalytic activity for ammonia synthesis was studied. The results show that when the high specific surface area SiC of 113 m2·g-1 is used as support, the prepared SiC-supported ruthenium catalyst has a relatively high activity(11.85%) under Ru 4wt%, Ba 4wt%, K 8wt%, 475 ℃, 10.0 MPa and 10 000 h-1.展开更多
文摘氨分解作为一种很有前景的现场制氢技术,关键在于开发出廉价、高性能的催化剂。本研究通过共沉淀法合成系列Ni_(x)Mg_(75–x)Al_(25)类水滑石化合物(HTlc)作为前驱体,经过焙烧和还原处理制备负载型高分散Ni/Mg(Al)O催化剂并用于氨分解制氢,采用不同研究手段对样品进行了表征,考察了Ni含量和氨还原对催化性能的影响。结果显示,HTlc前驱体经过焙烧分解形成Mg(Ni,Al)O固溶体,Ni物种与载体之间存在较强的相互作用,经750℃氨还原得到高分散Ni金属纳米颗粒,其平均晶粒尺寸为5.9~7.7 nm。质谱分析表明,氨还原过程中无氮氧化物(NOx)生成,同时750℃氨还原与氢还原催化剂的活性相当,说明氨是一种合适的还原气。催化剂活性随着Ni含量和还原温度升高而增加。其中,750℃氨还原Ni_(20)Mg_(55)Al_(25)催化剂在30000 m L·g^(–1)cat·h^(–1)、600℃下的氨转化率为98%,且在100 h反应过程中转化率保持不变,Ni金属无明显烧结现象,催化剂表现出良好的活性、稳定性和抗烧结性能。
文摘A sol-gel process catalyzed by oxalic acid was used for the preparation of SiC precursor from raw materials of tetraethyl orthosilicate (TEOS) and sucrose. The precursor thus obtained was homogeneous. Sintered with a certain heating program in an argon flow, the precursor was converted into the high surface area SiC. The high specific surface area silicon carbide was used as catalyst support for ammonia synthesis. The effect of the surface of the support, promoter and the amount of Ru on the catalytic activity for ammonia synthesis was studied. The results show that when the high specific surface area SiC of 113 m2·g-1 is used as support, the prepared SiC-supported ruthenium catalyst has a relatively high activity(11.85%) under Ru 4wt%, Ba 4wt%, K 8wt%, 475 ℃, 10.0 MPa and 10 000 h-1.
