Microchannel Plate Reactor: Principles, Advantages and Advances in Applications

I. Introduction

With the continuous progress of science and technology, there is a growing demand for efficient, precise and safe reactors in chemical reaction engineering. As a new type of micro-chemical equipment, microchannel plate reactor has emerged, with its unique microstructure and excellent performance, it has gradually become the hotspot of research and application in many fields, and has brought innovation opportunities for traditional chemical production and emerging technology fields.

II. Structure and Principle of Microchannel Plate Reactor

(i) Structural features

The core component of the microchannel plate reactor is the microchannel plate, usually made of metal, ceramic or polymer, etc., on which a network of micron or even nanometer-sized channels is etched, machined or molded. The size of these channels is very small, generally the width of the channel in tens of microns to several millimeters between the depth to match, the channel crisscrossing the formation of complex and regular fluid pathway system, the adjacent channels through the very thin wall separation, to ensure good sealing at the same time conducive to the exchange of heat. The reactor has a stacked plate structure, which makes it easy to increase or decrease the number of plates flexibly according to the demand of processing capacity, and each plate is equipped with precise inlet and outlet connectors for material introduction and export.

(ii) Principle of operation

The materials enter the micro-channel from their respective inlets at a precisely controlled flow rate, and the fluid flows in a laminar state at a tiny scale. This laminar flow characteristic avoids the common phenomenon of mixing back in the macro reactor, so that the molecules of the reactants can move forward in an orderly manner according to the established path, which greatly improves the uniformity of the concentration distribution of the reactants; at the same time, due to the extremely short distance between the channel wall and the fluid, the heat conduction efficiency is greatly improved, and the heat generated or absorbed in the process of the reaction can be rapidly transferred out or supplemented in to accurately maintain the temperature required for the reaction, which provides an ideal environment for all kinds of temperature-sensitive reactions. The temperature conditions required for the reaction are precisely maintained, providing an ideal environment for all kinds of temperature-sensitive reactions, greatly accelerating the reaction process and guaranteeing the reaction selectivity.

III. Advantages of microchannel plate reactor

(i) Excellent heat transfer performance

微通道巨大的比表面积(可达传统反应器的数百倍)结合极薄的通道壁，热传递阻力极小。例如在强放热反应中，能瞬间移除反应热，有效防止局部过热引发副反应或热失控危险，让反应始终在设定温度区间平稳进行，像精细化工中某些硝化反应，传统釜式反应器因散热不佳易导致多硝化杂质生成，而微通道板式反应器可将硝化产物选择性提高 20% - 30%。

(ii) High mass transfer efficiency

Micro-scale material diffusion distance is short, molecular diffusion rate is fast, and laminar flow to promote the rapid renewal of reactant molecules in contact with the interface, the mass transfer coefficient compared to traditional equipment to improve several times or even tens of times. Take gas-liquid reaction as an example, in the micro-channel bubble dispersion uniformity and small size, gas-liquid contact area increases dramatically, such as in carbon dioxide absorption experiments, micro-channel plate reactor absorption rate is 5 - 8 times that of the bubbling tower reactor, greatly shortening the reaction time, and enhance the production capacity of the equipment.

(iii) Precise response control

The stable laminar flow pattern of the microchannel and the precise fluid control technology can realize the real-time precise injection of reactants at specific ratios and flow rates, together with the sensitive on-line monitoring system, the reaction conditions can be dynamically adjusted. For complex organic synthesis steps, the reaction parameters can be controlled from the starting material to the final product, reducing the accumulation of impurities caused by reaction fluctuations and significantly improving the purity of the product, which is especially suitable for the synthesis of pharmaceutical intermediates with high value-added and demanding purity requirements.

(iv) Intrinsic safety features

Because of its extremely low liquid holding capacity (usually only a few microliters to a few milliliters per channel), even if an accidental reaction goes out of control, the hazardous material inventory is small, the instantaneous release of energy is small in scale, significantly reducing the risk of explosion, leakage and other serious accidents, which is in line with the increasingly stringent norms and requirements of chemical safety, and has outstanding advantages in the handling of flammable, explosive, toxic and hazardous materials, which provides a solid guarantee for the safe operation of the chemical industry.

IV. Application areas of microchannel plate reactors

(i) Chemical synthesis

It is widely used in the field of fine chemicals and specialty chemicals, such as spices, pesticides, liquid crystal material synthesis. Taking a new type of pesticide as an example, the multi-step reaction is carried out continuously in a microchannel plate reactor, which not only reduces the production cycle from the traditional days to hours, but also increases the product yield from 70% to more than 90%, and reduces the content of impurities to less than half of the national standard limit value, which significantly improves the product quality and economic benefits.

(ii) Biopharmaceuticals

It is suitable for enzyme-catalyzed reactions, cell culture and rapid drug screening. In monoclonal antibody production, microchannels accurately regulate nutrient supply and metabolic waste removal to maintain a stable cell growth environment, with cell densities 30% - 50% higher than traditional bioreactors, and antibody expression increased by about 2 times, which accelerates the process of new drug R&D, reduces R&D costs, and contributes to the development of biopharmaceutical innovation.

(iii) Energy conversion and storage

In the field of fuel cells, the microchannel plate reactor efficiently manages the supply of fuel and oxidant and the discharge of reaction water to improve the power density and stability of the battery; in the preparation of electrode materials for lithium-ion batteries, the precise control of co-precipitation and crystallization process prepares active materials with uniform particle size and regular structure, which dramatically improves the charging and discharging performance of the batteries and their cycle life, and pushes the new energy technology to a new level.

V. Challenges and future prospects

Despite the significant advantages of microchannel plate reactor, it is still facing some difficulties. Equipment manufacturing cost is high, micromachining technology is complex, the material and processing precision requirements are extremely high, resulting in a large initial investment; channel easy to block, small size of the material purity sensitivity, once the impurities mixed or product crystallization precipitation easy to cause channel obstruction, maintenance difficulties; industrial amplification of the existence of technological bottlenecks, from the laboratory flux to the large-scale industrial production, fluid dynamics, heat and mass transfer laws of the precise amplification The model is still not perfect, limiting its rapid industrialization and popularization.

Pomegranate Chemical specializes in microchannel continuous flow photochemistry! Looking ahead, with the continuous innovation of micro-nano manufacturing technology, the material cost is expected to be reduced, and the processing technology will become more mature and efficient; the cross-fertilization of multiple disciplines will give rise to breakthroughs in the research and development of intelligent self-cleaning and self-adaptive microchannel systems to solve the clogging problem; with the help of big data and deep mining of computational fluid dynamics, mature and reliable amplification guidelines and simulation software will be gradually established, which will help the micro-channel plate reactor enter the era of large-scale industrial application, and become the most popular micro-channel plate reactor for the chemical and related industries. It will help the microchannel plate reactor to enter the era of large-scale industrial application, become the core equipment for the transformation and upgrading of chemical and related frontier industries, and deeply rewrite the future pattern of chemical reaction engineering.