(280c) International Collaborations in the Field of Laboratory- and Pilot-Scale Micro-Reactor Plants

Micro-reactor technology is an interdisciplinary topic, involving skills from simulation, mechanical engineering, chemical engineering, chemistry, catalysis, and more. Such fields of expertise hardly can be covered by a single group today. Rather, collaborations and networking are an essential part of the business to bring the research developments into industrial application. For example, the high loading and large turnover in microstructured catalytic reactors demand for the development of new, highly active catalysts, rendering joint efforts of catalyst and microfab experts superior to isolated strategies based on simple supply of commercial material. In this paper, some successful examples about such joint activities of IMM with both academia and industry will be given. Typically, laboratory-scale developments are made in the scientific investigations, while such results are exploited with industry currently up to the pilot-scale level.

Collaboration with academia

IMM stands for know-how in simulation, manufacturing, and chemical micro reactor and process engineering. An R&D project of the European Community gave the chance of merging the expertises in homogeneous catalysis of the French institute CPE/CNRS (Villerbanne-Lyon) and of liquid-liquid and gas-liquid micro-reactor processing at IMM. In this way, a novel continuous micro-flow screening process was developed, enabling a fast testing of libraries of substrates and catalysts for the allyl alcohol isomerization and asymmetric hydrogenation of cinnamic acid esters.

A co-operation between the University College London (UCL) and IMM brought together expertise in simulation, hydro dynamics, catalyst testing and gas-liquid processing, respectively. In this way, for the first time a gas-liquid-solid micro reactor process, the hydrogenation of nitrobenzene over Pd/Al₂O₃, was realized using a falling film reactor. Particular concern was given to achieve stable catalysts and how to re-activate them. In addition, hydrodynamic measurements to determine the film shape were done and compared with film theory.

The experience of IMM in mixing with microstructured mixers and the competence of ECPM (Strasbourg) both in polymer reaction kinetics and polymer synthesis / characterization was bundled for the investigation of free and controlled (living) styrene radical polymerisation, the latter using alkoxyamines and nitroxides as initiator. In this way improved molecular weight distributions close to the ideal values, verified both by experiment and theory, could be achieved. Also, an understanding of the coupling of mass transport, hydrodynamics and reaction in a system with fast changing parameters was obtained.

Contract research with chemical industry

The Chinese Class I big state-owned enterprise Xi'an Huian Chemical Industry Co., Ltd. (HAC), situated near Xi'an, is a large-scale producer of fine, specialty and bulk chemicals. The company is engaged mainly in the products cellulose and its ramification, paints and organic solvents. HAC and IMM decided to establish a long term co-operation to explore possible applications of micro reaction technology for the production of fine chemicals and specialties and signed a R&D agreement this year. This co-operation started with developing a continuously working nitro-glycerin production using IMM pilot plant technique with integrated micro mixer-heat exchangers. In a second step, a purification system with a closed water cycle for the raw nitro-glycerin product is explored.

Developments with Trust Chem Co., Ltd., one of the biggest producers of specialty chemicals in China, were concerned with improving the azo pigment Yellow 12 synthesis. Changing such synthesis from batch to a semi-continuous process using mixing and precipitation with IMM microstructured mixers lead to smaller particle sizes and narrower particle size distributions. Consequently, the color properties of the pigment such as the glossiness and transparency were affected positively, yielding an improved product. Currently, this co-operation is continued with more demanding particle syntheses, performed by several European researchers at the industrial site in China.

Clariant (Frankfurt), a leading fine- and functional-chemicals manufacturer, wanted to achieve process intensification for the synthesis of phenyl boronic acid as an intermediate for electronic materials. The previous production method required harsh cooling conditions (cryo operation) and nonetheless lead to several side and consecutive products. By improving the mixing with microstructured devices the development of a better controlled process under more convenient operation conditions was expected. Using the respective synergies between Clariant and IMM, the synthesis process could be successfully changed and a pilot plant with a micro mixer could be realized. Improving the yield by more than 20% facilitated down-stream purification in such a way, that the whole distillation step was omitted, rather using now only extraction at room temperature.

The direct synthesis of hydrogen peroxide from the elements in the explosive regime was the aim of a contract research done for UOP (Chicago), a company licensing petrochemical processes and respective catalysts. UOP's interest was to have this direct route in the framework of the propylene oxide manufacture. Important were here IMM's skills in safe plant operation within the explosive regime with microstructured apparatuses. In this way, a safe direct route to hydrogen peroxide at reduced pressure (30 bar), favorable O₂/H₂ ratios close to 1, and high space-time yields was developed, accompanied by determination of CAPEX and OPEX costs. A basic engineering was made for a plant in the range of more than 100,000 t/a.