New technologies transform carbon dioxide into high-value “treasures””

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New technology turns carbon dioxide into high-value \"treasures\" Author/Source: Science and Technology Daily Date: 10-11-2019 Clicks: 8 When it comes to carbon dioxide (CO2), people generally consider it to be useless waste; not only is it of little use, but it is also one of the main culprits behind climate disruption and global warming. To date, researchers have come up with many ways to deal with it, such as confining it (sealing it in place) or putting it in an underwater prison (drilling into the seabed). However, in the eyes of Zhang Xiangping, a researcher at the Institute of Process Engineering, Chinese Academy of Sciences, CO2 is an excellent raw material – inexpensive and readily available. For over a decade, the ion liquid team she belongs to has, under the leadership of Academician Zhang Suojiang, been working on ways to efficiently convert and utilize CO2, turning waste into a valuable resource. 　　To deal with stubborn people, assign activists as “lobbyists”. The utilization of CO2 is a major global strategic issue. In June 2016, the EU launched a plan to make CO2 utilization a key area of research ； Japan has formulated a roadmap for CO2 utilization ； China’s **National Development and Reform Commission and the Energy Administration have listed it as a key task to be addressed in the Action Plan. However, due to issues such as the difficulty in activating CO2 molecules, complex reaction pathways, and low product selectivity, their activation and conversion have become one of the internationally recognized scientific challenges. 　　“CO2 is a common compound in the air, and converting it for use is not an easy task. We know that a CO2 molecule is composed of two oxygen atoms and one carbon atom connected by strong double bonds; it is quite difficult to break these tightly bound carbon-oxygen double bonds in order to reduce them to oxygen and carbon. ”Zhang Xiangping said in an interview with a reporter from Science and Technology Daily. 　　Zhang Xiangping further explained that the direct bond-breaking activation of CO2 requires high temperature and pressure; however, if other active molecules can be found to act as \"catalysts\", such as epoxides, then the activation of CO2 can be induced, making its transformation easier. In addition, a \"medium\" is needed, namely an appropriate catalyst, to facilitate the efficient conversion of CO2. 　　Over the past decade, through countless experiments and attempts, the research team has gradually identified an effective catalyst that fulfills its role – an ionic liquid catalyst based on the synergistic action of multiple active sites. This catalyst can not only activate the double bond in CO2 but also make ethylene oxide (EO), which reacts with it, more reactive and easier to open up. As a result, CO2 and EO can react together to produce important chemical intermediates such as ethylene carbonate. 　　Zhang Xiangping pointed out that by further loading through chemical bonds, the team successfully developed immobilized ionic liquid catalysts, thereby avoiding the problems associated with homogeneous catalysts, such as easy loss of activity, difficulties in catalyst recovery, high energy consumption, and impacts on product quality. 　　Creative solutions are devised to enhance value through efficient utilization. Once efficient catalysts have been developed, reactors that are compatible with them are also needed to provide an appropriate environment for the reactions to take place. 　　Zhang Xiangping explained, \"By following the principles of reaction-flow-transfer coupling, the team optimized the internal components of the reactor to achieve a uniform distribution of the flow field and temperature field. They developed a 10,000-ton capacity solid-supported ionic liquid gas-liquid-solid three-phase tubular reactor. The heat generated rapidly during the reaction can be discharged from the system quickly, preventing the reactor from overheating and ensuring safe operation.\" ” 　　On this basis, the research team adopted a coupling technique of alcoholysis reaction and pressure-swapped azeotropic distillation to achieve optimized integration of the entire system’s heat network, thereby significantly reducing energy consumption, improving economic efficiency, and lowering equipment investment. 　　“From a process perspective, it is also necessary to design a complete workflow that links together the entire reaction and separation processes in order to obtain the final qualified product from the raw materials. ”Zhang Xiangping told the reporters, “We optimized and integrated materials and energy throughout the entire process, which led to improvements in terms of energy consumption, efficiency, cost-effectiveness, and product quality, thereby meeting the needs of enterprises and the market.” ” 　　It is reported that, with the support of the key research program \"Clean and Efficient Utilization of Coal and New Energy-Saving Technologies,\" the project \"New Technologies for the Efficient Synthesis of Important Chemicals from CO2,\" led by the Institute of Process Engineering of the Chinese Academy of Sciences, has been underway since May 2018. In this project, functional ionic liquid catalysts with multiple active sites were designed and synthesized for use in CO2 carbonylation reactions, enabling the efficient conversion of CO2 under mild conditions. Meanwhile, carbonylation catalysts that meet industrial requirements were developed, and continuous reaction systems were established ； For the hydrolysis of vinyl carbonate, highly active and low-cost catalysts were developed, a 10-ton/year continuous hydrolysis plant was built, and an industrial pilot plant with a capacity of tens of thousands of tons was established. 　　Paving new paths for the synthesis of various important chemicals. CO2 capture, utilization, and storage (CCUS) technology is one of the key methods for reducing carbon emissions from coal use in China. Making efficient use of the captured CO2 not only helps to reduce carbon emissions and mitigate the greenhouse effect but also generates significant socioeconomic benefits. 　　Through years of relentless effort, driven by original innovations in catalysts, optimizations of reactor design, and integrated innovations in system design, the ionic liquid team at the Institute of Process Engineering, Chinese Academy of Sciences, has developed a new process that uses CO2 and the high-energy substance ethylene oxide as raw materials to synthesize vinyl carbonate. This compound is then subjected to alcoholysis to produce dimethyl carbonate, while ethylene glycol is obtained as a by-product, thus enabling the high-value utilization of these materials and representing a new technology for the mild conversion of CO2 with full atom utilization. 　　Just like turning stone into gold, the products derived from CO2 are all high-value \"treasures\" with a wide range of applications and promising market prospects; however, there have been challenges such as poor economic returns in previous attempts to utilize them. 　　Zhang Xiangping explained that among the various products available, dimethyl carbonate is primarily used in the synthesis of important intermediates in the organic chemical industry. It is regarded as the \"new cornerstone\" of green chemistry in the 21st century, and can be widely utilized in organic synthesis reactions such as carbonylation, methylation, methoxylation, carbonyl methylation, and polycarbonization. In recent years, with the rapid development of industries related to lithium-ion batteries and polycarbonates, the demand for dimethyl carbonate has been increasing steadily. China’s demand is expected to reach 4 million tons by 2020, and exceed 10 million tons by 2030 ； Ethylene glycol is a raw material for synthesizing polyester fibers and resins; China’s annual demand for it exceeds 14 million tons, with a dependence on imports of over 60%. 　　Industry experts believe that, compared to reaction pathways that involve the direct conversion of CO2 into chemicals, this technology offers significant advantages such as milder reaction conditions, good atom economy, and broad prospects for industrial application. The implementation of this project is of great strategic significance as it helps China seize a leading position in international CO2 utilization technologies, addresses and overcomes the bottlenecks in the clean and efficient use of coal in China, and opens up new paths for the high-value utilization of CO2.