New Type Of So <sub> 4 </ Sub> ~ (2 -) / M <sub> X </ Sub> The O <sub> Y </ Sub> Solid Super Acid Catalyst And Its Catalytic Organic Reactions Research

As a green catalyst, solid superacid has many advantages such as high catalytical activity, non-polluting, non-corroding, and being easy to be separated from reaction mixture. It is this kind green industrial catalyst that is helpful to the environment protection and possesses wide prospect of application. As a result, the study of solid superacid is a hotspot in industrial catalyst field.Although many people have engaged in researching solid superacid, especially, many effords have given on the preparation of the SO₄^2-/MxOy solid superacid and its use in organic reactions. But this kind of solid superacid is not widely used in industry because of the difficulties in preparation and separation. The present study mainly focuses on the preparation of new type SO₄^2-/MxOy solid superacid, which can be used in industry, and its application in the synthesis of piperazine, alkylpyrazine, 1,4-dioxane, tetrahydrofuran, etc. The major aspects of the present study are as follows:1. Preparation and analysis of soild superacidUsing ZrOCl₂ and H₂SO₄ as the starting materials, a series of catalysts of the SO₄^2-/ZrO₂ solid superacid were prepared under different conditions. The acid strength, specific surface area and the structure of acid center of them were studied by using Hammett indicator, N₂ sorption analysis applying BET method and FT-IR spectroscopy. The catalytic activities of the catalysts were characterized by the esterificational reaction. The results show that the SO₄^2-/ZrO₂ solid superacid with micro-crystal form, greater surface area and minimal acid density has better effect. There are two kinds of structures in SO₄^2-/ ZrO₂ solid superacid: the bridge type double coordinating structure and the chelate type double coordinating structure. In the low sulfuric acid loading concentration (≤2.5mol/L), the chelate type double coordinating structure is the main product. So the chelate type double coordinating structure plays a more important role in catalytical activity. The optimum preparation of the SO₄^2-/ZrO₂ solid superacid is: 0.5mol/L H₂SO₄ concentration, baking temperature at 600℃, and the catalyst has the highest catalytic activity.In order to fit the industrial catalyst field, granular SO₄^2-/M_XO_Y solid superacid was prepared by loading a little active carrier onto the granular fundamental carrier (such as Al₂O₃), and this granular catalyst was used in the flow-bed or fixed-bed reactors successfully.2. Study of organic catalytic used the catalystUsing the newly prepared catalysts, many experiments were carried out in order to study the application of the solid superacid. Among them, esterification reaction, cyclization reaction by water-elimination of alcohol, cyclization reaction by ammonia-elimination of diamine, etc were well studied. In this study, piperazine, alkylpyrazine, 1,4-dioxane and tetrahydrofuran etc were prepared successfully using only one open-chain material in the fixed-bed reactor. It indicated that the solid superacid is fit for the fixed-bed reactor and the flow-bad catalytic methodology, and has a bright prospect in industrial application. A possible mechanism for the reaction of alkylpyrazine is also suggested.