Green Chemistry View Article Online CRITICAL REVIEW View Journal | View Issue CO2-fixation into cyclic and polymeric carbonates: principles and applications Cite this: Green Chem., 2019, 21, 406 Aeilke J. Kamphuis, Francesco Picchioni and Paolo P. Pescarmona * The reaction between carbon dioxide and epoxides is an attractive pathway for CO2-utilisation as it can lead to the formation of two different, yet valuable, products: cyclic and polymeric carbonates. In this review, the advancements made within this field are critically discussed with special attention to the potential of these two classes of compounds as green chemical products. First, an overview is provided of the various types of homogeneous and heterogeneous catalytic systems developed for achieving the reaction of carbon dioxide with epoxides with high activity and selectivity towards either the cyclic or the polymeric carbonate products. Then, the chemical and physical properties of the cyclic and polycarbonate products Received 2nd October 2018, are discussed, focussing on the correlation between such properties and the potential applications of Accepted 2nd January 2019 each class of compounds. Finally, the most relevant applications of these materials, both potential and Creative Commons Attribution-NonCommercial 3.0 Unported Licence. DOI: 10.1039/c8gc03086c industrially implemented, are critically reviewed covering the fields of polymer products, energy storage rsc.li/greenchem devices, and biomedical and pharmaceutical applications. 1. Introduction character of a chemical product, ranging from the substitution of hazardous components of an existing product with safer In current chemical product development, the focus of and more sustainable alternatives, to the design and develop- research lies increasingly on environmental friendliness and ment of completely novel green chemical products. Incentives This article is licensed under a overall sustainability. Various ways exist to improve the green for the development of these chemical products can stem from various origins, such as the ambition to design a safer manu- facturing process, to decrease the dependence on depleting Chemical Engineering group, Engineering and Technology institute Groningen fossil resources or to reduce waste generation during the pro- Open Access Article. Published on 02 January 2019. Downloaded 9/29/2021 10:36:49 PM. (ENTEG), Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands. E-mail: [email protected] duction and disposal stages. Criteria and guidelines for these Aeilke J. (Arjen) Kamphuis was Francesco Picchioni was born in born in Marum, in the Terni, Italy. In 1996 he received Netherlands, and studied his MSc degree in Chemistry Chemical Engineering at the from the University of Pisa, University of Groningen where he together with a diploma from the obtained his BSc degree in 2012 Scuola Normale Superiore. In and his MSc degree in 2014. In 2000 he obtained his PhD in the same year he started his PhD Polymer Chemistry from the research at the University of same university. After 3 years as Groningen under the supervision post-doc researcher at the of Prof. Dr. Paolo P. Pescarmona Technical University of and Prof. Dr. Francesco Eindhoven, he became Assistant Aeilke J. Kamphuis Picchioni. His research interests Francesco Picchioni Professor at the University of lie in the development of novel Groningen, where he was and sustainable chemical products obtained from renewable appointed as Full Professor in Chemical Product Technology in resources. His PhD project focuses on the catalytic conversion of 2013. His research interests include thermally reversible networks, CO2 into cyclic and polymeric carbonates. polymer processing in supercritical CO2, bio-based polymeric materials and water-soluble polymers for Enhanced Oil Recovery. 406 | Green Chem.,2019,21,406–448 This journal is © The Royal Society of Chemistry 2019 View Article Online Green Chemistry Critical Review ambitions are summarised by the ‘Twelve Principles of Green Table 1 Global industrial CO2 emissions in 2014 from: fuel combustion 1 Chemistry’. The utilisation of carbon dioxide as a building (including all industrial energy-related CO2 emissions), fugitive emissions (mostly consisting of flaring of non-marketable gas during oil and gas block for chemical products has the potential to fulfil many of production) and industrial process emissions (including non-energy these principles and, accordingly, is receiving growing atten- 8 generation of CO2 in i.a. the cement industry and ammonia production) tion from the academic community, from industry and, more in general, from the whole society. CO2 is a renewable and Amount of emitted CO2 Source of CO emission (Mtonnes per year) abundant C1-feedstock and is inexpensive as it is being gener- 2 2–4 ated as a waste gas in enormous quantities globally (the Fuel combustion 32 381 total worldwide CO2 emissions were estimated to be 36.2 Power and heat production 13 625 billion tonnes in 2015).5 Being the most oxidised form of Fuel used in the extraction and refining of 1683 fossil feedstock carbon, it is extremely stable and hence non-toxic and non- Manufacturing industries and construction 6230 3,4,6 a flammable. Although chemically rather inert, CO2 can act Transport and other sources 10 843 b as a greenhouse gas by absorbing a fraction of the radiation Fugitive emissions 483 Industrial processesb 2468 emitted by the Earth and then re-emitting it towards the a planet.7 Therefore, the increasing emissions of carbon dioxide Such as commercial/institutional activities, agriculture/forestry, fishing and residential. b Data from 2010. in the atmosphere have been identified as one of the main – causes of global warming.8 10 Various strategies have been con- sidered in order to counter the accumulation of anthropogenic CO2 in the atmosphere, including improving energy efficiency from the conversion of CaCO3 into CaO), the iron and steel and minimising heat losses, increasing the usage of fuels with industry, the oil and gas industry (where non-marketable gas low or no carbon content (e.g. hydrogen) and of renewable is flared, and hence is converted into CO2) and ammonia pro- energy sources, applying climate engineering approaches (e.g. duction.5,8 Conceptually, CCU represents a very attractive ff Creative Commons Attribution-NonCommercial 3.0 Unported Licence. reforestation and a orestation), carbon capture and storage/ option in the context of carbon neutrality and of a circular sequestration (CCS) and carbon capture and utilisation economy.12 However, a number of hurdles need to be over- 10 (CCU). The latter refers to processes aimed at capturing CO2 come before this approach can be implemented. Although at the location where it is emitted and at reusing it, so that it technologies are available to capture high amounts of CO2 will not enter the atmosphere. The capture is typically limited with an efficiency of over 80% from large CO2 emitters such as to localised industrial emissions with high CO2 concentration, power plants and cement factories, full-chain technologies whereas recovering carbon dioxide from, e.g., residential and including capture, separation, transport and utilisation are transportation sources would be technologically, logistically still quite costly.10 Additionally, the final utilisation step rep- 10,11 and economically more demanding. The largest industrial resents a relevant challenge because the conversion of CO2 is This article is licensed under a 13–15 source of CO2 emissions is represented by power plants based limited by its high thermodynamic and kinetic stability. on fossil fuel combustion (Table 1). Other major sources for The thermodynamic stability can be overcome by reacting CO2 CCU include the cement industry (where CO2 is generated with high-energy substrates such as hydrogen, amines or 3,14,16–19 Open Access Article. Published on 02 January 2019. Downloaded 9/29/2021 10:36:49 PM. epoxides, or by providing an energy input in the form of heat,20 electric current21 or radiation;22 whereas the kinetic barrier can be overcome by employing a suitable catalyst for Paolo P. Pescarmona was born in the chosen conversion reaction. The conversion of carbon Torino, Italy. He received his dioxide into fuels is a very attractive option, in view of the MSc degree in Chemistry from large-scale applicability and because it would allow reconvert- the University of Torino in 1997 ing CO2 into the same kind of compounds from which it was and his PhD from the Delft generated, leading to a circular carbon economy and thus University of Technology in helping to prevent the accumulation of anthropogenic CO2 in 2003. From 2005 to 2014 he the atmosphere. The possible products of CO2 reduction worked at the University of include, in increasing order of reduction degree, CO, formic Leuven, first as post-doc acid, formaldehyde, methanol and higher alcohols, methane researcher and since 2008 as and higher hydrocarbons.23,24 All these products are indust- Assistant Professor. In 2014 he rially relevant, but only those with higher degree of reduction moved to the University of can be employed as fuels. The reduction of CO2 can be carried Paolo P. Pescarmona Groningen, where he is currently out either through direct reaction with H2 or through an Associate Professor in electrochemical or photochemical route: Sustainable Chemical Products and Catalysis. His research inter- • The reaction with H2 has been widely studied and