The Structure And Property Of AlOOH In The Reaction Of CO Hydrogenation

Coal has caused severe damage to environment while it has brought great economic benefits to our country. At present, the high efficiency and clean utilization of coal is the key factor to change this situation in our country. And the research and development of coal clean conversion and utilization technology with independent intellectual property rights is a strong support point for the transformation. The research that the synthesis gas from coal（SNG） was converted into clean fuels of higher alcohols is one of the hot topics in modern coal chemical industry. It is also an efficient way to achieve the transformation of development model from "black" to "green".In our previous work, CuZnAl catalyst prepared by complete liquid-phase technology could significantly improve the catalytic activity for CO hydrogenation and the selectivity of ethanol. It was founded that the existence form of Al in CuZnAl catalyst prepared by complete liquid-phase technology was AlOOH, not γ-Al2O3. However, the structure and catalytic properties of AlOOH has not been systematically studied. Inthis paper, AlOOH which was synthesized by hydrothermal precipitation method and homogeneous precipitation method were mixed with industrial methanol synthesis catalyst C302, and then were investigated for CO hydrogenation in the fixed-bed reactor. Furthermore, the CuZnAl catalyst was prepared by one step precipitation method in this paper.Meanwhile, the effects of different precipitation agents, raw materials ratio and hydrothermal temperature on their structure and catalytic properties were investigated. These researches could benefit to comprehending the catalytic performance of AlOOH in the synthesis of higher alcohols. In this paper, the catalysts were characterized by XRD,BET, FT-IR, H₂-TPR, NH₃-TPD-MS, CO₂-TPD-MS, TG-DTG, the main conclusions are summarized as follows:1、The composite catalysts that AlOOH made by hydrothermal precipitation method（named as C-n） and homogeneous precipitation（named as U-m） was mixed with C302 showed a relatively high selectivity of higher alcohols in CO hydrogenation. The conversion of CO can reach 14.8% and the selectivity of C²⁺OH was 13.5% for the composite catalysts C-2+C302. However, the conversion of CO reached31.9% and the selectivity of C²⁺OH was 11.2% for the U-4+C302. The results showed that AlOOH with proper ratio of weak and strong acid sites, larger pore volume was suitable for increasing the catalytic activity.In addition, mechanical mixing had an effect in the existence form of Cuspecies.2、The CuZnAlOOH catalyst made by one step precipitation method showed an activity for CO hydrogenation which produced higher alcohols.The selectivity of C²⁺OH was similar with the composite catalysts, but the activity decreased at the same time, due to the difference interaction between CuZn component and Al component. The conversion of CO could reach 4.2% and the selectivity of C²⁺OH was 12.9% when the molar ratio of CuZnAl was 2:1:0.8.3、The CuZnAl catalyst with HTLcs structure had a higher activity than the CuZnAlOOH to synthesize higher alcohols, the conversion of CO could reach 12.5% and the selectivity of C²⁺OH was 13.8% when the molar ratio of CuZnAl was 0.4:0.6:1. These results offer a new idea for the catalyst in the synthesis of higher alcohols.