Study On Preparation Of SO₄^2-/ZrO₂ Solid Acid Catalysts By Microwave Heating And Their Application In Esterification Reactions

At present, green chemistry has become the hot topic in chemistry industry. The defects of difficult separation of liquid acid with system, serious equipment erosion, environmental pollution, etc. have been overcome by the employment of solid superacid catalysts. Therefore, the solid superacid catalyst, which has been widely used in organic reaction, is an environmentally friendly catalyst and has enormous application prospect in future.Usually, solid acid catalysts need to be roasted at high temperature during the preparation. The generated consume is huge, which is obeyed with the realization of green chemistry. The technique of microwave heating as a new heating method is approved to be high-speed, efficient, energy-saving, environmentally friendly and easy to operate. This technique has been widely used in areas of inorganic, organic, environment, catalyst, material chemistry, etc.In this study, the starting point is to manufacture catalyst with high performance through applying the microwave heating technology to the preparation of SO42- /MxOy type solid acid catalyst. This catalyst is modified by the addition of rare earth oxide and molecular sieve and analyzed by characterization. At the same times, associating catalytic activity to the results of characterization to gain a better solid superacid. Based on these considerations, the main research as following:Firstly,Single phase type SO₄^2- /ZrO₂ solid acid catalyst was prepared by microwave heating. Tetragonal ZrO₂ crystalline phase of this catalyst is more stable than the catalyst prepared by heating in muffle furnace. The existence of the metastable tetragonal ZrO₂ crystalline phase exhibits high catalytic activity to the Synthesis of butyl lactate from lactic acid and butyl alcohol. Correlation of catalytic activity and ZrO₂ crystalline phase is studied. The reusability property of catalyst is fine.Secondly, SO42- /ZrO₂-Nd₂O₃ sulfated binary oxide solid acid catalysts modified by rare earth were prepared. The experiment indicates that doping Nd₂O₃ the stabilization of tetragonal ZrO₂ crystalline phase. The introduction of rare earth oxides increased the number of acid center on catalyst surface and strengthened the acidity of catalyst. Synthesis of butyl lactate from lactic acid and butyl alcohol by this catalysts is studied. The experiment indicates that this solid acid exhibits higher catalytic activity than single phase type SO₄^2- /ZrO₂ solid acid catalyst,and the reusability property and stabilization of catalyst is fine.Thirdly, SO₄^2- /ZrO₂-HZSM-5 solid acid catalysts were prepared. This new type of catalyst exhibits the higher acidity than SO₄^2- /ZrO₂ catalyst since that HZSM-5 molecular sieve has some acidity and its enormous pore structure increases the coordination absorption of SO42- .Synthesis of butyl acetate from acetic acid and butyl alcohol by this catalysts is studied, and the reusability property and stabilization of catalyst is fine.Fourthly, the transformation of crystalline phase was characterized by FT-IR,TG-DTA,XRD and so on. Realizing catalyst crystal microscopic controllable adjustment to obtain solid superacid with higher catalytic activity,selectivity and stabilization.At the same time, carrying on an investigation into correlation of catalytic activity and crystalline phase.