| The catalytic synthesis of propanal by ethene hydroformylation is an important research, which has important theoretical and applied value. As an important kind of fine chemicals, propanal has been extensively used in many fields which include pesticide. medicine, food, textile et at., and the demand of propanal is very large, so the commercial apply of propanal is promoting. However propanal has not been produced in commercial process in our country. The research about catalytic synthesis of propanal can promote the development of industry of fine chemicals. Synthesis propanal by ethene hydroformylation is a homogeneously catalyzed reaction performed industrially on a large scale, and becomes a main process by which propanal is produced. Because it's difficult to make catalyst separation and recycling. so many research efforts have been made to avoid this step by using heterogeneous catalysts in recent years. However, the activity and selectivity of heterogeneous catalysts are lower than homogeneous catalysts? so increasing the activity and selectivity of heterogeneous catalyst become the most difficult and the key problem in this research field. In this dissertation, with supported Rh catalyst system as research object, the preparation methods of catalysts and added promoter were investigated, which aiming at adjusting the composition and the structure of catalysts. to improve the activity and selectivity of catalysts. The main progresses are as follows: Thermodynamic analysis of ethene hydroformylation was first carried out. The results of analysis show the main and side reactions were intensively exothermic reactions, and ethene hydrodcalkylation is the side reaction, which predominated on the thermodynamics and intensively compete with the main reaction. Increasing the selectivity of catalyst and control of reaction conditions are the key in order to get target products. The results of analysis also indicate that increasing reaction temperature is advantageous for ethene hydrodcalkylation. and increasing pressure is advantageous for ethene conversion. The results of experiments prove the results of thermodynamic analysis. Fifteen kinds of Rh-Mo/SiO,. Rh-NiISiO2, Rh-Co/Si02 catalysts were designed and prepared by co-impregnation of Si02 with RhC13 3H2O Co (NO3) 2 61]QO . Ni (NO3) 2 6H)O.. (NH4) 6Mo7O24 4 H2. The activity and selectivity of Rh-Mo/SiO,. Rh-Ni/Si02. Rh-Co/SiO, catalyst had been studied by ethene hydroformylation (using a molar ratio of C2H4:CO:H2=1 :1:2) which was carried out in a fixed bed tubular reactor at I 80 2.0MPa 2000W1. The results show: the reaction properties of Rh-Mo/SiO-, were relatively low for ethene hydroformylation. The selectivity for hydroformylation is only 26.300 over 1 % Rh-Mo-,/SiO-,. The conversion of ethene was obviously increased by using Rh- Ni/SiO,. and the selectivity for hydroformylation was also increased. 200 Rh- Ni-/SiO-, can give the selectivity for propanal is 60.7%. The conversion of ethene is increased over Rh-Co/Si&,. and the selectivity for propanal and propanol were also increased. 2% Rh-Co,/Si02 can give an ethene conversion of 31.6% ,and the selectivity for hydroforrnylation is 84.70o, for propanal is 60.60o. for propanal is 24.1 00 . This result breaks the result in literature: the selectivity for hydroformylation is 77 %. It was observed that reaction conditions effect the reaction property of Rh-Co!SiO, catalyst. Increasing reaction tem... |
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