Study On The Reactions For Synthesis Of Fine Chemicals And Mixed Law In Microreactor

Safe, clean, efficient, energy-saving and continuous production will be the trend of the development of chemical industry in the21st Century. Microchemical technology is a novel technology using microreactor in chemical reactions, to realize green synthesis through strengthening process. Compared with traditional batch reactor, microchemical technology has many advantages, such as high speed mixing, efficient heat transfer, short residence time, good repeatability, quick response, facilitate automation, almost no amplification effect and high safety performance, which makes it becomes one of the research hotspots in Chemical Engineering. The PTFE microreactor, glass microreactor and stainless steel microreactor were design and made. The reactions for synthesis of fine chemicals and mixing law of process in microreactor were studied in the dissertation.A model study was initiated with C.I. acid red54as substrate. The coupling reaction for synthesis of azo dyes was studied in a microchannel reactor. The effects of the reaction flow rate, the residence time, the pipe inner diameter and the reaction temperature on the single-pass conversion and selectivity were evaluated. The optimum process parameters were selected as follows:at room temperature, molar ratio of diazo components to coupling components1:1, flow rate0.18m/s, residence time11.11s, tube diameter1.0mm. The yield reached to96.80%. These conditions also applied in the synthesis of C.I. Acid Yellow23, C.I. Acid purple1, C.I. reactive red35, C.I. Reactive yellow16. The products yield of acidic series is up to95%, and up to80%for reactive dyes.A model study was initiated with toluene as substrate. The oxidative bromination of toluene derivatives with HBr-H2O2as brominating agent was studied in PTFE tube and glass tube microchannel reactors. The effects of molar ratio, residence time, and light intensity on the single-pass conversion and selectivity were evaluated. The optimum process parameters in PTFE-microreactor were selected as follows:molar ratio of toluene to H2O2to HBr2:1.5:1, incandescent light100W, residence time5minutes. The utilization rate of bromine atom reached to66.5%, target product’s selectivity reached to93.1%. For glass-microreactor, the optimum conditions were selected as follows:molar ratio of toluene to H2O2to HBr2:1.5:1, incandescent light150W, residence time5minutes. The utilization rate of bromine atom reached to93.6%, target product’s selectivity reached to94.0%. The optimum reaction conditions were also applied to oxidative bromination of other alkylbenzenes with getting a better utilization rate of bromine atom and selectivity. The result showed that this process and HBr-H2O2system has a great value of usage.A model study was initiated with chlorobenzene as substrate. The nitration of aromatics with nitrate-sulfuric acid as nitrating agent as nitrating agent was studied in stainless steel microchannel reactor. The effects of molar ratio, volume flow rate, reaction temperature on the single-pass conversion and selectivity were evaluated. The optimum process parameters in PTFE-microreactor were selected as follows:the molar ratio of chlorobenzene to nitric acid1:1.3, the ratio of nitric acid to sulfuric acid1:3, reaction temperature80℃, chlorobenzene’s volume flow rate0.5mL/min. The single batch conversion rate of chlorobenzene reached to74.8%. The ratio of o-nitrocholobenzene to p-nitrocholobenzene was about0.56. The optimum reaction conditions were also applied in other aromatic compounds. The results showed that it was significantly improved for the ratio of o-nitrocholobenzene to p-nitrocholobenzene and decreased for byproducts. The space-time conversion (STC) in microreactor was about3.08×104times than that in conventional reactor.A model study was initiated with C.I. acid red54as substrate. Reynolds (Re) and Segregation index (Xs) as mathematical model, the micro-mixing was studied. The effects of flow rate, inside diameter on the micro-mixing were evaluated. The results showed that the flow rate effecting on Re and Xs existed a critical value, when the number exceeded this value, the flow rate effect was no longer significant. Under the optimum flow rate, inside diameter had little influence on Xs and tends to a stable value. At the same time, any one of Reynolds (Re) was greater than critical Reynolds (Rec).In summary, though the study of typical fine organic reaction, such as coupling, oxidative bromination, nitration reaction and its mixing law, it was get a conclusion that micro-technology could not only improved the production efficiency greatly, but also increased the stability, safety, operability of the process. The microreactor technology is an effective method to realize safe, clean, efficient, energy-saving and continuous production for fine organic synthesis. Thus, the research of application basis for microreactor technology can lay a theoretical basis for industrialized efficient and green production.