China Scientific Research Team： New Technology Makes Carbon Dioxide High-value ＂Baby＂

　　Take the "life gate" in your own hands.

　　When it comes to carbon dioxide (CO2), people generally think that it is like waste wood, which is not only useless, but also one of the chief culprits of destroying the climate and causing global warming. So far, researchers have thought of many ways to deal with it, such as imprisoning it (curing and sealing it) and driving it into a water dungeon (drilling into the seabed). However, in the eyes of Zhang Xiangping, a researcher at the Institute of Process Engineering of China Academy of Sciences, CO2 is a good raw material, which is cheap and easy to obtain. For more than ten years, her ionic liquid team, under the leadership of Academician Zhang Suojiang, has been pondering how to efficiently convert and utilize CO2 and turn it into treasure.

　　Deal with stubborn guys and send activists as "lobbyists"

　　CO2 utilization is a major global strategic issue. In June 2016, the EU launched a plan to take CO2 utilization as a major research direction; Japan has formulated a road map for CO2 utilization planning; China’s National Development and Reform Commission and Energy Bureau listed it as a key task in the Action Plan. However, the activation and transformation of CO2 molecules has become one of the internationally recognized scientific problems due to the problems of difficult activation, complex reaction path and low product selectivity.

　　"CO2 is a common compound in the air, and it is not easy to transform and utilize it. As we know, CO2 molecule is made up of two oxygen atoms and a carbon atom connected by a solid double bond, if you want to ‘ Knock ’ It is quite difficult to open the carbon-oxygen double bond closely linked between them and reduce it to oxygen and carbon. " Zhang Xiangping said in an interview with the Science and Technology Daily reporter.

　　Zhang Xiangping further explained that direct bond-breaking activation of CO2 requires high temperature and high pressure, but if we can find other active molecules to be lobbyists, such as epoxy compounds, we can induce the activation of CO2 and make its transformation easier. In addition, it is necessary to add a "medium", that is, a suitable catalyst, to promote the efficient conversion of CO2.

　　In the past ten years, after many experiments, the research team has gradually found an effective "cadre" who will live up to its mission — — The ionic liquid catalyst with multiple active sites can not only activate the double bond of CO2, but also make the ethylene oxide (EO) that reacts with it become active and open the ring more easily, so that CO2 and EO can react together to synthesize ethylene carbonate, an important chemical raw material.

　　Zhang Xiangping pointed out that the team successfully prepared the immobilized ionic liquid catalyst through further chemical chain loading, which avoided the problems of easy loss and deactivation of homogeneous catalyst, difficult catalyst recovery, high energy consumption and impact on product quality.

　　Coup after coup, enhancing value for efficient use.

　　Efficient catalyst has been developed, and a matching reactor is needed to provide a suitable place for the reaction.

　　Zhang Xiangping said: "Compliance response — Flow — According to the law of transfer and coupling, the team optimized the internal components of the reactor, realized the uniform distribution of the flow field/temperature field, and innovatively developed a 10,000-ton ionic liquid gas-liquid-solid three-phase tubular reactor, and the heat released quickly during the reaction can be discharged from the system as soon as possible, so that the reactor does not overheat and realizes safe operation. "

　　On this basis, the research team adopted alcoholysis reaction — The coupling process strengthening technology of pressure swing azeotropic distillation can realize the optimal integration of the whole system heat network, greatly reduce energy consumption, significantly improve economy and reduce equipment investment.

　　"In terms of technology, it is necessary to design a whole process to connect the whole reaction and separation process in order to get the final qualified product from raw materials." Zhang Xiangping told reporters, "We have optimized the integration of material and energy in the whole process, and greatly improved energy consumption, efficiency, economy and product quality to meet the needs of enterprises and markets."

　　According to reports, with the support of the national key R&D plan "Clean and Efficient Utilization of Coal and New Energy Saving Technology", since May 2018, the project "New Technology for Efficient Synthesis of Important Chemicals by CO2" led by the Institute of Process Engineering of Chinese Academy of Sciences has designed and synthesized a functional ionic liquid catalyst with multiple active sites in the CO2 carbonylation reaction, realizing efficient conversion of CO2 under mild conditions. At the same time, a carbonylation catalyst meeting industrial needs has been prepared and a continuous reaction device has been built. Aiming at the alcoholysis reaction of vinyl carbonate, a catalyst with high activity and low cost was developed, a 10-ton/year alcoholysis continuous device was built, and a 10,000-ton industrial test device was established.

　　Open up a new path to synthesize multiple important chemicals

　　The technology of CO2 capture, utilization and storage (CCUS) is one of the main ways to realize low-carbon emission of coal in China, and the high-value utilization of the collected CO2 can not only reduce carbon emission and alleviate the greenhouse effect, but also produce significant social and economic value.

　　After years of unremitting efforts, through the original innovation of catalyst, the optimization of reactor structure and the integrated innovation of the system, the ionic liquid team of Institute of Process Engineering of Chinese Academy of Sciences has developed a new route of synthesizing ethylene carbonate from CO2 and high-energy material ethylene oxide, and then producing dimethyl carbonate and ethylene glycol by alcoholysis respectively, forming a new all-atom utilization technology of mild conversion of CO2.

　　Just like turning the stone into gold, products produced by CO2 are all high-value "treasures", which have a wide range of application fields and considerable market prospects, but there are problems such as poor economic benefits after being used before.

　　Zhang Xiangping said that among diversified products, dimethyl carbonate is mainly used to synthesize important organic chemicals, which is known as the "new cornerstone" of green chemistry in the 21st century. It can be widely used in organic synthesis reactions such as carbonylation, methylation, methoxylation, carbonyl methylation, polycarbonates, etc. In recent years, with the rapid development of power lithium batteries, polycarbonates and other related industries, the demand for dimethyl carbonate continues to grow rapidly, and the demand in China is expected to be 4 million tons in 2020. Ethylene glycol is a raw material for the synthesis of polyester fiber and resin. China’s annual demand is more than 14 million tons, and its dependence on foreign countries is more than 60%.

　　According to the insiders, compared with the reaction route of direct conversion of CO2 into synthetic chemicals, this technology has obvious advantages such as mild reaction conditions, good atomic economy and broad industrialization prospects. The implementation of the project will help China seize the international commanding heights of CO2 utilization technology, solve and break through the bottleneck problem of clean and efficient utilization of coal in China, and open up a new path for high-value utilization of CO2, which has important strategic significance. (Reporter Hua Ling)