Study On Synthesis And Properties Of 2-Ethylhydrazine And Tetraalkylurea In Hydrogen Peroxide Process

Hydrogen peroxide(H2O2)is one of important inorganic chemical materials,it is called the "cleanest chemical product" because it essentially non-polluting to the environment during production and using process.At the end of 2018,the productivity of hydrogen peroxide to China has reached 13.73 million tons.Hydrogen peroxide is widely used in the chemical,textile,papermaking,defense,electronic,medical,environmental protection and other industries as oxidant,bleaching agent,disinfectant,etc.The anthraquinone process is the only method for the large-scale production of hydrogen peroxide as it has the advantages of low cost,easy control and recyclability.Working fluid consists of 2-ethyl anthraquinone(2-EAQ)working carrier and a mixed solvent for dissolving 2-EAQ and its hydrogenated product plays an important role in anthraquinone process.Therefore,the development of 2-EAQ green synthesis process and new high-efficiency solvent have important significance and practical value for the green development of hydrazine method.On the one hand,the current industrial production method of 2-EAQ is phthalic anhydride method,which uses a strong dehydrating agent oleum to catalyze the ring-closing reaction of 2-(4'-ethylbenzoyl)benzoic acid(abbreviated as BE acid).It will produce a large amount of waste acid containing organic matter,which seriously pollute the ecological environment and cause huge safety hazards;it has become one of the bottlenecks in the process of hydrogen peroxide production.On the other hand,the solvent currently used consists of nine carbon aromatic hydrocarbons and trioctyl phosphate(TOP);however,trioctyl phosphate has low solubility for effective hydrazine,which makes it difficult to give full play to the catalytic ability of the hydrogenation catalyst,and directly restricts the production efficiency and production capacity of a single hydrogen peroxide production unit.In view of the two key problems of the above-mentioned bismuth hydrogen peroxide process,this thesis mainly studies the development of a new process for non-cigarette sulfuric acid green catalysis of 2-ethyl hydrazine and the synthesis and properties of new high-efficiency solvents.The main work of this paper is as follows:(1)According to the reaction mechanism of the ring-closing reaction of BE acid and based on the chlorine group is a good leaving group,a two-step green process using acyl chloride as an intermediate has been developed(first,conversion of BE acid to acyl chloride;and then catalytic acyl chloride undergoes ring-closing reaction to obtain 2-EAQ).This work focusing on synthesis conditions of acyl chloride,and exploring the effect of acyl chloride content on the purity of 2-EAQ,and implementing a 100-kilometer pilot production test for the 2-EAQ green process in a two-step process.The results show that the content of acyl chloride in the acylation solution has a great influence on the quality of 2-EAQ,the purity of 2-EAQ increases as the content of acyl chloride increases;The optimum synthesis temperature of acid chloride is 40? and the optimum reaction time is 15 min,Under the condition,the conversion of BE acid can reach over 97%,and the selectivity of acid chloride is over 95%;The yield and purity of crude 2-EAQ in the pilot production are 90.8%and 96.12%;The purity of the crude product can reach 99%after the impurity removal treatment,which meets the national standard of 2-EAQ.(2)The tetra-butyl urea solvent has a large solubility for the effective anthraquinone,but the separation speed of the working fluid and the water is slow during the hydrogen peroxide extraction process,thereby greatly reducing the production efficiency.In order to solve this problem and choose an excellent solvent,a series of C2?C6 branched-chain tetra-alkyl urea with different carbon numbers were designed and synthesized.The structure-activity relationship between their physicochemical properties such as density and micelle size and their solubility to 2-EAQ and the separation speed of their corresponding working fluids and water were systematically studied.The results show that the density difference of tetra-alkyl urea solvent increases with the increase of the number of carbons in the branch,while the aggregation ability of the molecule and the solubility of the anthraquinone decrease with the increase of the carbon number of the branch.The interaction between density difference and molecular aggregation ability causes the separation speed of tetra-alkyl urea working solution and water to decrease first and then increase with the increase of the number of branched carbons.In the series of tetra-alkyl urea,tetra-ethyl urea solvent has a faster separation speed and the best solubility,and the solubility of anthraquinone is much larger than TOP,the separation speed is comparable to that of TOP.It is expected to replace TOP in the anthraquinone working fluid system.