Editorial pubs.acs.org/CR
Introduction: Chemicals from Coal, Alkynes, and Biofuels
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gas, Higman and Tam have described the peculiarities for processing coal and gas. Then the production of alcohols, MEG, acetyls, waxes, etc. is presented with an interesting discussion of process description and commercial plants. The authors end up with a section which shows that, despite the fact the production of chemicals from coal via gasification is a well described and mature industry, there is still room for improving the technology, and research continues in this field. Nevertheless, one cannot forget that most of the coal used today is burned off to produce energy, leaving CO2 as a subproduct. Since CO2 emissions should be decreased and work in CO2 activation is a timely research line, this thematic issue also includes an authoritative review by Aresta et al. on the valorization of CO2 by conversion into chemicals and fuels. In this sense the authors discuss thermal and catalytic processes for producing chemicals such as urea, inorganic and organic carbonates, carbamates, acrylates, etc. The authors conclude that the use of biotechnology and natural or hybrid “man made photosynthetic microorganism” for CO2 fixation and for converting CO2 into carbon rich species is one way to approach the issue. As was said before, alkynes and, more specifically, acetylene is a chemical that can be produced from coal, and it was of much interest to build a part of the chemistry in the first part of last century. However the acetylene chemistry was replaced by the chemistry of ethane and propene, produced from oil and natural gas. The large reserves of shale gas will certainly favor the production of olefins but also that of acetylene. Therefore, it is of interest to search for new processes that make possible the future use of acetylene. This is already persuaded by different companies and academic laboratories. Furthermore, the reactivity of acetylene and acetyls, together with the development of new catalysts and processes starting with alkynes, make this an interesting topic to be treated here. In the present thematic issue we have two excellent reviews, presented by Schobert and by Trotuş et al., which focus on the conversion of acetylene into a large variety of chemical products. The authors discuss new homogeneous and heterogeneous catalysts, as well as potential new microreactor technologies. It is stated that the use of acetylene should not be seen as a step back, but as a diversification of the chemical industry. In fact, Chinchilla and Nájera have widely shown the richness of the chemistry of alkynes. Then, they present how well designed palladium catalysts can build up interesting and useful molecules by inter- and intramolecular additions to alkynes and finally the use of alkynes in C−C coupling reactions. This review has shown the possibility of preparing a variety of starting materials for producing a very large number of compounds of academic and industrial interest by starting with alkynes and the adequate palladium catalyst. Biomass is a renewable source of carbon. It can certainly be broken down into its components and, after removing oxygen
e had in mind, up to not a long time ago, that the time roadmap for producing hydrocarbon based chemicals was marked historically and by a matter of reserves by the sequence coal → oil → heavy oil-TarSands → coal, with a part of those chemicals being also produced by natural gas. However, environmental reasons and the discovery of huge reserves of natural gas by fracking techniques have completely changed the previous long-term strategy by introducing biomass and natural gas as important raw materials in the pool of carbon-containing molecules for production of chemicals. It appears then that, in the coming years, both fossil fuels and renewable sources of carbon, such as biomass, will be the basic suppliers for production of chemicals. Though the activation and transformation of alkane C1 and C4 gases generated by fracking is a hot subject today, we would like to review the possibilities of coal and biomass, to produce chemicals that are otherwise difficult to produce from gas and even, sometimes, from oil. Following this idea, the present thematic issue has reviewed first the possibilities of coal to produce chemicals through the main process: coking (pyrolysis), liquefaction, and gasification. The first part of the volume will start with a very exhaustive work by Morgan and Kandiyoti on the fundamentals for the thermal breakdown of coal and biomass. This work is a key to follow and understand the knowledge generated on the reactions occurring during coal and lignocelluloses biomass pyrolysis. The discussion on the reaction pathways and the influence of reaction conditions, and detailed product analysis and techniques thereof, not only help to understand and explain product distributions, but can also be inspiring on how to direct the reactions to produce the most desired chemical products obtained by this technology. The introduction of different reactor configurations and reaction parameters nicely completes this review. After this more fundamental review, Granda et al. describe how it is possible to obtain chemicals, from the coal coking process, with molecular structures not easy to find in chemicals obtained from other sources.The authors describe the methods to produce liquid fractions from coal which are enriched with aromatics, how to separate them, and their use for producing polymers and pitches. The way of producing liquids with high H/C ratios from coal is by either removing carbon or by introducing H2. Then, after presenting the methodologies to obtain liquid fractions by coke removal (pyrolisis), Mochida et al. have deeply discussed the way of producing liquid fractions for the fuels and chemicals by coal liquefaction (hydrogenation). An excellent description of aromatic, oxygen−nitrogen, and sulfur containing chemicals, as well as double-, triple-, and multi-heteroatom compounds in coal liquids and extracts, and their chemical applications has been given. A third way to produce chemicals from coal is via synthesis gas from coal gasification. Though the processes for producing chemicals from synthesis gas are the same, regardless of whether the synthesis gas is obtained from coal or from natural © 2014 American Chemical Society
Special Issue: 2014 Chemicals from Coal, Alkynes, and Biofuels Published: February 12, 2014 1545
dx.doi.org/10.1021/cr400719e | Chem. Rev. 2014, 114, 1545−1546
Chemical Reviews
Editorial
and adding hydrogen, can be converted into liquid fuels. Much emphasis has been devoted in the last years to the transformation of biomass to fuels. However, it appears that the building blocks of biomass, either directly or conveniently transformed, could find an excellent use to produce chemicals. It is clear that with this methodology one should not make efforts to remove the oxygen, but obtain biomass oxygenated chemicals of much interest. The transformation of biomass into chemicals has been tackled in this thematic issue through three authoritative reviews by Besson et al., Straathof, and Mäki-Arvela et al. The authors have shown how it is possible, through the use of enzymes, cells, or inorganic catalysts, to transform not only the basic components of the lignocellulosic material, but also a series of platform molecules, into alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, lactones, nitriles, amines, amino acids, and further products derived from them. The impact of the natural or synthetic catalysts on the reaction mechanism and the possibilities for optimizing conversion, selectivity, and catalyst life are profusely studied, showing the already very large number of biomass derived chemicals that can be achieved starting from biomass and biomass derived products. This is a less usual thematic issue in which the possibility of producing chemicals from sources other than the most conventional oil and oil fractions is analyzed. I believe that it is a thematic issue that shows the diversity, richness, and power of chemistry for producing more complex organic molecules starting from any source of carbonaceous molecules.
catalysts. He has published more than 900 research papers and is an inventor on more than 100 patents. Corma earned his B.S. in Chemistry at Valencia University, earned his Ph.D. at Madrid under the direction of Prof. Antonio Cortes, and spent two years as a postdoc at Queen’s University. He has received the Ciapetta and Houdry Awards of the North American Catalysis Society, the F. Gault Award of the European Catalysis Society, the M. Boudart Award on Catalysis by the North American and European Catalysis Societies, the G. J. Somorjai ACS Award on Creative Catalysis, the Breck Award of the International Zeolite Association, the National Award of Science and Technology of Spain, the ENI Award on Hydrocarbon Chemistry, the Royal Society of Chemistry Centenary Prize, the Rhodia Pierre-Gilles de Gennes Prize for Science and Industry, the Gold Medal for the Chemistry Research Career 2001−2010 in Spain, La Grande Médaille de l’Académie des sciences de France 2011, and Honour Medal to the Invention from the Fundación Garciá Cabrerizo in Spain 2012.
Avelino Corma
Instituto de Tecnologı ́a Quı ́mica (CSIC-UPV)
AUTHOR INFORMATION Notes
Views expressed in this editorial are those of the author and not necessarily the views of the ACS. Biography
́ Avelino Corma, Professor at the Instituto de Tecnologiá Quimica (CSIC-UPV), has been carrying out research in heterogeneous catalysis in academia and in collaboration with companies for nearly 30 years. He has worked on fundamental aspects of acid−base and redox catalysis with the aim of understanding the nature of the active sites, and reaction mechanisms. With these bases have developed catalysts that are being used commercially in several industrial processes. He is an internationally recognized expert in solid acid and bifunctional catalysts for oil refining, petrochemistry, and chemical processes, especially in the synthesis and application of zeolite 1546
dx.doi.org/10.1021/cr400719e | Chem. Rev. 2014, 114, 1545−1546
