Preparation Of Nickel-based SBA-15 Catalyst Based On Confinement Effect And Study Of CO 2 Methanation Performance

Reforming of methane with carbon dioxide to produce synthesis gas(H2 / CO ratio of about 1), which used as materials for Fischer-Tropsch synthesis to produce liquid fuel, synthesize methanol and dimethyl ether. At the same time, CO2 is a reforming reactant, which reduces greenhouse gas emissions to a certain extent. It is significant that using CO2 as a carbon source for resource conservation and recycling economy.In this paper, molecular sieve SBA-15 was used as a catalyst support material, and nickel-based catalyst was prepared by loading nickel element onto the mesoporous pore of SBA-15. The catalyst exhibited a high conversion rate for CO2 and high selectivity for methane owing to its confinement effect. The main content of the following three aspects of the experimental results are as follows:1) The effects of different types of acids, such as hydrochloric acid、 nitric acid and sulfuric acid and also research on the Effects of different concentration of hydrochloric acid on the preparation of SBA-15. The results showed that when the hydrochloric acid, nitric acid and sulfuric acid were used respectively, the molecular sieve SBA-15 had ordered mesoporous structure, and the specific surface area of the three were: 436 m2g-1、363 m2g-1、312 m2g-1;the pore size were: 3.8 nm、3.6 nm、3.9 nm;the SBA-15 were found to have highly ordered mesoporous structure while investigating the amount of different hydrochloric acid. The specific surface area of 10 m L, 15 m L, 20 m L, 25 m L, 30 m L with HCl were respectively:616 m2g-1、360 m2g-1、358 m2g-1、436 m2g-1、391 m2g-1;the pore size were:4.95 nm、4.55 nm、4.58 nm、4.61 nm、4.43nm。It is concluded that the molecular sieve SBA-15 synthesized by 25 m L has a more regular ordered mesoporous structure, and has a better specific surface area and pore size: 436 m2g-1, 4.61 nm.2) The structure and catalytic performance of the catalysts prepared by different nickel content, different solvents, different acid treatment, and different preparation methods and post treatment methods were investigated. The results showed that 7% nickel in Ni/SBA-15 presented the best catalytic performance. Combined with TPR and BET analysis and catalyst activity evaluation method, it was found that 7%Ni/SBA-15 has a large number of nickel particles into the molecular sieve pore, resulting in the confinement effect: 61.5%、70%. When using acetone solvent, the conversion of 7%Ni/SBA-15 to CO2 and the selectivity of CH4 were optimal when 350℃ was 350℃, the conversion rate was 67.81%, and the selectivity of CH4 was 83.90% when 400℃ was. Using oxalic acid, citric acid treatment, catalyst 7%Ni/SBA-15 at 350 ℃ transformation and CH4 to CO2 selectivity are optimal: 350℃ conversion rates were 75.21, 70.00% and 400℃ selectivity of CH4 is 84.49%, 88.98%, which indicates that in acetone as the solvent, oxalic acid, citric acid were on catalyst of 7%Ni/SBA-15 has a good role in promoting. The conversion of CO2 to 350℃ and the selectivity of CH4 were optimal when 7%Ni/SBA-15 was used as catalyst in the treatment of ultrasonic.3) Study on the treatment of 7%Ni/SBA-15 with different loading methods. Studies have shown that under the bet analysis, found in detection of H2-TPR analysis. It is found that the enhanced interaction of ultrasound after treatment catalyst, the Ni based and molecular sieve, which not only in the preparation of the catalyst on the saving time and cost, at the same time, for the oxidation catalyst reduction have been greatly improved, presumably, this will not only can reduce the cost of the preparation of the catalyst, and conducive to the catalyst deactivation due to coking effect was weakened to some extent.4) The catalysts with different Cu and Ni ratio supported on molecular sieve SBA-15 were investigated. The results showed that when the copper nickel ratio is 1:2. At this time, the catalyst still has good mesoporous structure and by TPR and XRD analysis, the copper and nickel loading reached maximum, reduction temperature decreased, the reduction of Ni O concentration increased. At this time, the catalyst for the conversion of CO2 and CH4 was higher than other catalysts: 400℃ conversion rate of 90%, the selectivity of CH4 was 98.90%.