Selective Catalytic Dehydration Of1,4-Butanediol To3-Buten-1-ol Over Alkaline Earth Metal Oxides Doped CeO₂Catalysts

3-Buten-l-ol (BTO) with double bond and hydroxyl, can participate in a variety of reactions such as esterification and addition reaction, and it is a valuable chemical that is widely used in the medical and fine chemical fields. BTO can be made from1,4-butanediol (BDO) selective dehydration over the metal oxides, and the route with potential for industrial application overcome high temperature, high pressure, low conversion rate and product separation difficulty of the previous preparation methods.The metal oxides that catalyze dehydration of BDO can be classified into two categories:acid basicity type catalyst and redox type catalyst. CeO2is favored by the researchers due to its good characteristic of redox. Research showed that the surface oxygen defects of CeO2are the active center of selective dehydration reaction of diols. It has been an important problem that how to change structure and surface properties of CeO2catalyst, and then improve the conversion of BDO dehydration and the selectivity of BTO.The previous research has shown that, through the control of the morphology of CeO2, the more oxygen vacancies exposed which is favor to BDO dehydration reaction. Basis on many literature investigation and previous research, a series of MO-Ce02catalysts that alkaline earth metal oxides doped CeO2were prepared. The catalytic performance of BDO dehydration reaction to BTO was investigated, and the catalyst structure and surface properties were characterized through XRD, TPR and TPD techniques. The influence of redox properties and surface basicity on the catalytic performance of the doping CeO2were discussed. Finally, this paper examines the influence of reaction conditions (including reaction temperature, catalyst dosage, velocity of BDO, etc.) on the dehydration performance of BDO over CaO-CeO2catalyst. The main results are as follows:1、The fluorite structure of CeO2, was not changed by alkaline earth metal oxide doping CeO2, but the oxygen defects of the catalyst were increased, thereby the catalytic activity of BDO selective dehydration were improved. With the increasing of M atomic number, the number of oxygen defects of MO-CeO2catalyst was decreased, and the improving activity degree of BDO conversion was reduced. Meanwhile, the introduction of the MO can produce more surface basicity sites, further improved the selectivity of BTO, and the order of the improving selectivity degree: CaO-Ce02>Sr0-Ce02>Ba0-Ce02>Mg0-Ce02. Among them, Ca2+and Ce4+showed the best compatibility, and the CaO-CeO2catalyst exhibited the highest selectivity of BTO and catalytic performance.2, In CaO-CeO2catalyst, Ca2+replaced Ce4+into the CeO2lattice and the lattice distorted, more oxygen defects in materials were produced, which resulted in the enhancement of its redox property. With the increase of the doped amount of CaO, the catalyst redox property first increased and then decreased, which was consistent with its catalytic activity of BDO selective dehydration; Meanwhile the basicity sites on the catalyst surface gradually increased, thereby the selectivity of BTO was increased, and3%CaO-CeO2catalyst showed the best catalytic performance. Therefore, in the CaO-CeO2system, redox property and basicity of catalyst combined impact the dehydration conversion of BDO and the selectivity of BTO.3、By investigating the effect of reaction conditions on selective dehydration of BDO over3%CaO-CeO2catalyst, it was found that the reaction temperature, catalyst dosage, velocity of BDO, etc had impact on the performance of selectivity dehydration of BDO. And the catalytic performance of3%CaO-CeO2catalyst was stable during the reaction time. The results showed that the optimal conditions of selective dehydration of BDO to BTO:reaction temperature was375℃, catalyst dosage was2g, the velocity of BDO was3.0mL/h, the velocity of carrier flow was30mL/min. On this conditions, the conversion rate of BDO was98.23%,&the selectivity of BTO was58.58%.