鈣鈦礦型LaNi1-xMgxO3觸媒應用於CH4/CO2重組反應之研究

Abstract

The methane reforming of carbon dioxide reaction could transform the greenhouse gas CH4 and CO2 into syngas CO and H2. The syngas could be used to produce methanol or some high value organic compounds. In order to enhance the reaction activity, stability, and carbon resistibility of the LaNiO3 catalyst used in the reforming reaction, the catalyst was prepared by citrate method and promoted by adding Mg, Ce or supported by α-Al2O3. Finally, LaNiO3, LaNi0.94Mg0.06O3, La0.96Ce0.04Ni0.94Mg0.06O3, and 5wt.% LaNi0.94Mg0.06O3 / α-Al2O3 catalysts would be discussed and compared in the catalytic performance. The LaNiO3 phase was formed at 600°C initially from precursor prepared by the cictrate method. The specific surface area and particle size were 9.06 m2/g and about 91.3 nm respectively of LaNiO3 catalyst pre-heated at 350°C for 0.5 h and calcined at 700°C for 2 h. The conversion of CH4 and CO2 were 76.2% / 77.9% respectively when LaNiO3 catalyst reacted at 700°C, but the reaction was forced to terminate due to the serious carbon deposition after 1 h. To improve the LaNiO3 catalyst used in the methane reforming of carbon dioxide reaction, magnesium was introduced as promoter to catalyst by two steps. First, the LaNi1-xMgxO3 catalyst was prepared by citrate method and discussed the best Mg adding content. And LaNi0.94Mg0.06O3 showed the best catalytic performance at 700°C, the CH4/CO2 conversion reached to 62.7% / 79.3%. Second, to improve the catalytic performance and carbon resistability of catalyst, the LaNi1-xMgxO3 catalyst was promoted by co-doping and supported method. In co-doping way, Ce was adding to LaNi0.94Mg0.06O3 catalyst with different content. And La0.96Ce0.04Ni0.94Mg0.06O3 showed the best catalytic performance at 700°C, the CH4/CO2 conversion reached to 75.9% / 91.4%. In supported method way, LaNi0.94Mg0.06O3 was supported by α-Al2O3 with particle size 200 nm. 1 g of 5wt. LaNi0.94Mg0.06O3 / α-Al2O3 catalyst showed the best catalytic performance, carbon resistability, and stability in different using amounts. The CH4/CO2 conversion reached to 88.9% / 98.1%. It was only 1wt.% carbon deposition amount after 2 h activity reaction. And it could maintain the activity and stability(duribility) after reaction at 700°C for 8 h. It was also superior in these four catalysts. Key words: Catalytic, LaNiO3, CH4, CO2, dry reforming.