Optimization Of Process For Preparing Fluorescent Whitening Agent CBS-351 And Its Industrial Design Of 500t/a

Fluorescent whitening agent is a kind of important fine chemical product, belongs to the optical colorless dye. Its action principle is whitening substance by using light effect. Its annual output and the dye production ratio is 0.1-0.12. Now for there are15 types,359 varieties, a total of more than 4000 models. It is widely used in chemical, textile, papermaking, synthetic resin and synthetic fiber industries. The production and use of fluorescent whitening agent is for a long time in China, now it has developed for more than a dozen varieties, production accounts for 4%?5% of dye. Its consumption composition is: about 1% of fluorescent whitening agent used in polymer synthesis,20% used in the textile industry,34% used in paper industry,45% used in daily chemical industry. At present, the domestic only used for detergent industry each year is about 10000 tons of brightening agent, fluorescent brightener CBS class accounts for about 1000 tons.Fluorescent brightener CBS-351 (hereinafter referred to as "CBS-351") and styrene biphenyl disulfonic acid sodium, formula is C34H28Na2O8S2. It is a kind of fluorescent dye, also known as white dye, anionic sex. Its structure is a kind of single and double conjugate structure of benzene derivatives. CBS-351 is not sensitive to chlorine bleaching, oxygen bleaching, the acid and alkali inertia, the sun is stable, because of excellent performance, it is mainly used in daily chemical cleaning products, especially in the different class of washing powder, soap, soap, laundry paste and liquid detergent. It can obviously improve the comprehensive performance.the internal and external quality of thing is improved. It is the best fluorescent whitening agent variety by global detergent industry recognized because of its excellent properties beyond other cosmetic type fluorescent whitening agent.At present, the product is prepared by biphenyl ldpe-g-nvp in China, synthesis of its total yield close to 75%, the product quality is improved obviously, but the preparation and energy consumption of economy is not ideal. Our research work is to replace low cost solvent, to improve the yield, to shorten production process of experiment, this paper discusses several aspects such as the comprehensive utilization of materials, and find a reliable solution, thus further industrialization design scheme is put forward.Research work can be specific divided into the following steps:the first step is intermediates esterification synthesis, the intermediate is also known as 4,4'-double (double ethoxy acid methyl) biphenyl. In the esterification reaction experiment, we take biphenyl dimethyl benzyl chloride, diethyl phosphite as raw materials, studied the relationship between reaction temperature, time, molar ratio, water effect on the yield of esterification reaction and by-products chloroethane recycle. In consideration of the energy consumption and economy, the optimization of the synthesis technology, we obtained the best process parameters:reaction temperature 168?, reaction time is 4h, diethyl phosphite with biphenyl dimethyl benzyl chloride mole ratio of 3:1, moisture less than 0.3%, the second step is the synthesis of CBS-351 under the condition of the system of moisture is less than 0.1%, the intermediate of esterification and adjacent benzene sulfonate sodium formaldehyde equably were dispersed in dimethyl formamide, drops of not less than 28% mass fraction of liquid sodium methoxide, control of reaction temperature, reaction time is 5-8h. when the reaction is end, solid-liquid separation, purification and filtration products CBS-351. The overall yield of two step reaction can reach more than 85%. In the process of the experiment we studied temperature, quantity of alkali, solvent amount, water, fine raw esterification and ester content impact on the synthetic yield of CBS-351, at the same time the reaction material post-processing and refined mother liquor recycling, to product quality and production process of reducing energy consumption material consumptions. The best reaction process conditions as follows:reaction temperature 40?, alkaline for esterification 2.5 times (Moore), amount of solvent for esterification 4 times (quality), moisture is less than 0.1%, the third step, we made a 500 t/a CBS-351 industrial plan simple design by combined with the data and the optimum process conditions in the experiment.