Design, Synthesis And Performance Of Rhodium-based Catalysts For Mixed-Alcohol Production And Their Ecological Environment Effect

The ecological environment deterioration, global warming and energy depletion are the most important problems that must be resolved urgently in the world. The only way to solve these problems is to explore efficient clean alternative energy with sustainable and environment-friendly production mode. The alcohol fuel is often regarded as a potential renewable clean alternative fuel to gasoline. The synthesis of mixed alcohols through the hydrogeneration of CO or CO2is widely considered to be one of the most prospective energy production modes because it has many advantages, such as the various choices of raw materials, the high energy efficiency and the less emissions of toxic and greenhouse gas during the consumption of the alcohol fuels. However, the industrialization of alcohol fuel synthesis through the hydrogenation of CO or CO2is still immature due to the low CO conversion and the low alcohol selectivity. The research and exploitation of more efficient catalysts are the most effective way to deal with these problems. For the synthesis of alcohol fuel through the hydrogenation of CO or CO2, the critical factor to improve the catalytic activity is to strengthen the interaction between active components and promoted metals as well as to control their dispersion states on the supports effectively. And these could be solved by introducing heterometallic coordination polymers as catalytic precursors into the above-mentioned system of alcohol production.Based on the above considerations, in this thesis, a series of heterometallic coordination polymers with different compositions, structures and functions were firstly constructed by rhodium ions, alkali-metal ions, lanthanide ions and pyridine carboxylic ligands. It should be noted that the alkali-metal ions and the lanthanide ions are always used as promoters in rhodium-based catalysts for the hydrogenation of CO or CO2. The synthesized Rh-M heterometallic coordination polymers as catalytic precursors were creatively introduced into the above-mentioned hydrogenation system to prepare corresponding catalysts. During the exploration of the catalytic performances for the hydrogenation of CO or CO2, the CO2utilization level and the greenhouse gases (CH4and CO2) emission level were evaluated as well. Moreover, the catalytic performances of these new-type rhodium-based catalysts for CH4and CO2reforming to syngas were explored, which provides the theoretical and practical basis for the combination of CO or CO2hydrogenation technology and CH4and CO2reforming technology. The study also provides a feasible solution for eliminating greenhouse gas emissions as much as possible during the hydrogenation process of CO or CO2.The main work is as follow.1. Eight new compounds were synthesized, including five Rh-M coordination polymers (RhLi(PDA)2(H2O)2-2H2O (1), RhNa(PDA)2(H2O)2(2), RhK(PDA)2(3), RhCe(BPTA)(H2O)4Cl2(4) and RhEu(BPTA)(H2O)4Cl2(5)), two novel supermolecules (Rh(BPDA)(HBPDA)(6) and Co(BPDA)(HBPDA)(7)) and a lanthanide coordination polymer (Eu2(BPDA)3(H2O)]·6H2O (8))(H2PDA=pyridine-2,6-dicarboxylic acid; H4BPTA=2,2'-bipyridine-3,3',6,6'-tetracarboxylic acid; H2BPDA=2,2'-bipyridine-6,6'-dicarboxylic acid). All the compounds were structurally characterized by single-crystal X-ray diffraction, and the properties of all compounds were examined.2. Six new-type rhodium-based catalysts were prepared using the six Rh-based coordination polymers as precursors, respectively, and their catalytic performances of CO hydrogenation were tested. The effects of the structures, the compositions of the precursors as well as the reaction conditions on catalytic performance were also explored. Furthermore, in order to explore the effects of the reaction conditions on catalytic performance, the catalyst1-SiO2derived from RhLi(PDA)2(H2O)2-2H2O (1) was used to synthesize alcohols through hydrogenation of CO and CO2.4. The CO2utilization level was evaluated during the synthesis of alcohols from the mixture of CO, CO2and H2, and the greenhouse gases (CH4and CO2) emission level was also evaluated during the synthesis of alcohols from the mixture of CO and H2and the mixture of CO, CO2and H2. The results show that all the catalysts gave the very low level of greenhouse gases emission, and they can be considered as green and environment-friendly.5. The experiment regarding CH4and CO2reforming to syngas was performed, and a production mode was simulated by coupling of the CO or CO2hydrogenation technology with CH4and CO2reforming process. The strategies of greenhouse gas emission reduction for the CO or CO2hydrogenation process were also proposed. The results provide experimental experiences and useful data to achieve the real combination of CO or CO2hydrogenation technology and CH4-CO2reforming technology.