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Photo-catalytic reduction of carbon dioxide to formate
N21
MTBE Production
Photo-catalytic Reduction of Carbon Dioxide to Formate
Methyl ten-butyl ether (MTBE) appears to be, so far at least, the most widely accepted of the various oxygenates manufactured for addition to gasoline, so as to raise the octane rating and also to increase gasoline volume. Perhaps this is not surprising as MTBE has both a high octane number and physical properties similar to hydrocarbons in the middle of the gasoline boiling range. With the increasing use of lead-free petrol across the world the addition of MTBE to gasoline provides the petroleum refiner with a valuable alternative to more severe processing. MTBE is manufactured from methanol and isobutene by a catalytic process, normally with an ion-exchange resin as catalyst. The European Fuel OxygenatesAssociation (EFOA) reports (Chem. Britain, 26 (1990) 540) that world capacity for MTBE will exceed 11.6m tonnes/year by the end of 1992. Operating capacity is currently 7.3m tonnes/year, from 54 plants, with most of this capacity in the U.S.A. (4m tonnes/year) and Western Europe (2.lm tonnes/year). Another eight plants, with total capacity of lm tonnes/year, were under construction last year in the U.S.A. and South America, and 21 plants, which will give capacity increases of lm tonnes/year in Canada, 560,000 tonnes/year in Western Europe and 500,000 tonnes/year in the Far East, are planned to be on stream by 1992. Several other projects are currently under consideration, so EFOA says “a further large extension of MTBE capacity is likely in the next decade”.
applied catalysis-Volume
63 No. 2 -22
The catalytic hydrogenation of carbon dioxide to methanol is one of the most important catalytic processes in the heavy chemicals industry and arguments over the details of the mechanism of the heterogeneous reaction have occupied many pages, in Applied Catalysis and elsewhere, without any sign yet of exhaustion setting in. The homogeneous photo-catalytic reduction of carbon dioxide has also been the subject of controversy and two recent papers (l-l. Ishida, T.Terada, K. Tanaka and T. Tanaka, Inorg. Chem., 29 (1990) 905; J.M. Lehn and R. Ziessel, J. OrganometalIic Chem., 362 (1990) 157) contain some interesting work on closely similar systems. The starting point for both groups of workers was discovery the that [Ru(bpy)#‘, where bpy = 2,2’-bipyridine, is an active photo-catalyst under visible light for the reaction. Both groups of workers have used 13CNMR to prove that the observed formate ion in solution is indeed produced by reduction of carbon dioxide and is not the product of some other reaction in the system. Both groups also find maximum quantum yields of about 15%. lshadaet al. followed the formation of carbon monoxide as well as formate and they concluded, from experiments with different solvent mixtures, that the selectivity for carbon monoxide and formate is mainly controlled by the reaction medium rather than the difference between the various ruthenium complexes, e.g., Ru(bpy)&ls and [Ru(bpy)2(CO),]2’. The electron donor in the system is triethanolamine (Ishada et al. also used 1-benzyl-l,cdihydronicotinamide). Lehn and Ziessel used either [Ru(bpy)g]2+ alone as both photosensitiser and homogeneous cata-
August 1990
N22
lyst or a mixture of (i) [Rub]‘+, where L= bpy derivatives or 1,lO-phenanthroline, as photosensitiser, and (ii) cis-[Ru(bpy) (CO)&I] or cis-[Ru(bpy),(CO)(X)]“+, where n=l for X=CI,H or n=2 for X=CO, Like lshadaet al., Lehn and Ziesselfindthat the efficiency of formate production depends on reaction medium - in this case, water and excess ligand - but they also observe that it is independent of carbon dioxide pressure. In their suggested mechanism a Ru(0) species is formed and in turn coordinates and then reduces carbon dioxide. Protonation of the bound-carbon dioxide complex is followed by reaction with chloride ion, so releasing the formate ion and regenerating the Ru bpy complex. All still rather far from an industrial process but nevertheless showing again the versatility of carbon dioxide as afeedstock.
Jacob Berzelius
Jacob Berzelius is one the few people who can be described with some justification as the Father of Catalysis, for he was the first to apply the known word “catalysis” to a range of related phenomena (he did not invent the word). Readers of Applied Catalysis will be (or should be) interested in a biographical article on Berzelius by Jan Trofast, advisory curator of the Berzelius Museum at the Royal Academy of Sciences in Stockholm (Chem. Britain, 26 (1996) 432). Catalysis gets only a single mention in the article, under a list of the achievements of Berzelius, which indicates the breadth of his contribution to chemistry. His development of analytical techniques enabled him to determine the atomic weights of some 40 elements and ascertain the composition of many compounds. He also isolated many new elements, e.g. cerium, selenium, thorium, silicon and zirapplied catalysis -
Volume 63 No. 2 -22
conium, and he contributed to the discovery of lithium and vanadium. He lived in exciting times. One aspect of Berzelius’ genius which Trofast emphasises is his skill as a practical chemist, both in the manipulations and planning of laboratory work: ‘The laboratory work changed at the beginning of the 19th century, because of the need for more accurate experiments. The chemists had to prepare or at least purify most of the chemicals themselves. ‘The caustic alkali from France is excellent for laundering, but not for chemical experiments”, Berzelius wrote in one letter. The work became more sophisticated .., chemists were ingenious in finding new ways of solving their problems. One of Berzelius’ important contributions to chemistry was the development of laboratory technique - his textbook remained an important laboratory handbook for nearly half a century”. Trofast also covers the personal aspects of Berzelius’ life. He grew up “under poor and uncertain conditions which taught him to believe in his own actions and decisions”. He was clearly “a balanced and upright member of society” with an “optimistic view of life and an astonishing stability and security”. Nothing of the manic eccentric here. However he emerges from all this sober portrayal in a letter he wrote a week after being married, for the first time at 56 to Elizabeth, the 24 year old daughter of a close friend: “It is rather curious to be married. I am on the whole most pleased with it. My everyday life is infinitely pleasant. This is also the main thing; the inevitable coteries are however a little tiring but I will probably get used to the idea of not being permitted to leave them when I like which is otherwise a valuable privilege for bachelors. Betty seems to like her new conditions well. She is very bright, brighter
August 1990
MTBE Production
Photo-catalytic Reduction of Carbon Dioxide to Formate
Methyl ten-butyl ether (MTBE) appears to be, so far at least, the most widely accepted of the various oxygenates manufactured for addition to gasoline, so as to raise the octane rating and also to increase gasoline volume. Perhaps this is not surprising as MTBE has both a high octane number and physical properties similar to hydrocarbons in the middle of the gasoline boiling range. With the increasing use of lead-free petrol across the world the addition of MTBE to gasoline provides the petroleum refiner with a valuable alternative to more severe processing. MTBE is manufactured from methanol and isobutene by a catalytic process, normally with an ion-exchange resin as catalyst. The European Fuel OxygenatesAssociation (EFOA) reports (Chem. Britain, 26 (1990) 540) that world capacity for MTBE will exceed 11.6m tonnes/year by the end of 1992. Operating capacity is currently 7.3m tonnes/year, from 54 plants, with most of this capacity in the U.S.A. (4m tonnes/year) and Western Europe (2.lm tonnes/year). Another eight plants, with total capacity of lm tonnes/year, were under construction last year in the U.S.A. and South America, and 21 plants, which will give capacity increases of lm tonnes/year in Canada, 560,000 tonnes/year in Western Europe and 500,000 tonnes/year in the Far East, are planned to be on stream by 1992. Several other projects are currently under consideration, so EFOA says “a further large extension of MTBE capacity is likely in the next decade”.
applied catalysis-Volume
63 No. 2 -22
The catalytic hydrogenation of carbon dioxide to methanol is one of the most important catalytic processes in the heavy chemicals industry and arguments over the details of the mechanism of the heterogeneous reaction have occupied many pages, in Applied Catalysis and elsewhere, without any sign yet of exhaustion setting in. The homogeneous photo-catalytic reduction of carbon dioxide has also been the subject of controversy and two recent papers (l-l. Ishida, T.Terada, K. Tanaka and T. Tanaka, Inorg. Chem., 29 (1990) 905; J.M. Lehn and R. Ziessel, J. OrganometalIic Chem., 362 (1990) 157) contain some interesting work on closely similar systems. The starting point for both groups of workers was discovery the that [Ru(bpy)#‘, where bpy = 2,2’-bipyridine, is an active photo-catalyst under visible light for the reaction. Both groups of workers have used 13CNMR to prove that the observed formate ion in solution is indeed produced by reduction of carbon dioxide and is not the product of some other reaction in the system. Both groups also find maximum quantum yields of about 15%. lshadaet al. followed the formation of carbon monoxide as well as formate and they concluded, from experiments with different solvent mixtures, that the selectivity for carbon monoxide and formate is mainly controlled by the reaction medium rather than the difference between the various ruthenium complexes, e.g., Ru(bpy)&ls and [Ru(bpy)2(CO),]2’. The electron donor in the system is triethanolamine (Ishada et al. also used 1-benzyl-l,cdihydronicotinamide). Lehn and Ziessel used either [Ru(bpy)g]2+ alone as both photosensitiser and homogeneous cata-
August 1990
N22
lyst or a mixture of (i) [Rub]‘+, where L= bpy derivatives or 1,lO-phenanthroline, as photosensitiser, and (ii) cis-[Ru(bpy) (CO)&I] or cis-[Ru(bpy),(CO)(X)]“+, where n=l for X=CI,H or n=2 for X=CO, Like lshadaet al., Lehn and Ziesselfindthat the efficiency of formate production depends on reaction medium - in this case, water and excess ligand - but they also observe that it is independent of carbon dioxide pressure. In their suggested mechanism a Ru(0) species is formed and in turn coordinates and then reduces carbon dioxide. Protonation of the bound-carbon dioxide complex is followed by reaction with chloride ion, so releasing the formate ion and regenerating the Ru bpy complex. All still rather far from an industrial process but nevertheless showing again the versatility of carbon dioxide as afeedstock.
Jacob Berzelius
Jacob Berzelius is one the few people who can be described with some justification as the Father of Catalysis, for he was the first to apply the known word “catalysis” to a range of related phenomena (he did not invent the word). Readers of Applied Catalysis will be (or should be) interested in a biographical article on Berzelius by Jan Trofast, advisory curator of the Berzelius Museum at the Royal Academy of Sciences in Stockholm (Chem. Britain, 26 (1996) 432). Catalysis gets only a single mention in the article, under a list of the achievements of Berzelius, which indicates the breadth of his contribution to chemistry. His development of analytical techniques enabled him to determine the atomic weights of some 40 elements and ascertain the composition of many compounds. He also isolated many new elements, e.g. cerium, selenium, thorium, silicon and zirapplied catalysis -
Volume 63 No. 2 -22
conium, and he contributed to the discovery of lithium and vanadium. He lived in exciting times. One aspect of Berzelius’ genius which Trofast emphasises is his skill as a practical chemist, both in the manipulations and planning of laboratory work: ‘The laboratory work changed at the beginning of the 19th century, because of the need for more accurate experiments. The chemists had to prepare or at least purify most of the chemicals themselves. ‘The caustic alkali from France is excellent for laundering, but not for chemical experiments”, Berzelius wrote in one letter. The work became more sophisticated .., chemists were ingenious in finding new ways of solving their problems. One of Berzelius’ important contributions to chemistry was the development of laboratory technique - his textbook remained an important laboratory handbook for nearly half a century”. Trofast also covers the personal aspects of Berzelius’ life. He grew up “under poor and uncertain conditions which taught him to believe in his own actions and decisions”. He was clearly “a balanced and upright member of society” with an “optimistic view of life and an astonishing stability and security”. Nothing of the manic eccentric here. However he emerges from all this sober portrayal in a letter he wrote a week after being married, for the first time at 56 to Elizabeth, the 24 year old daughter of a close friend: “It is rather curious to be married. I am on the whole most pleased with it. My everyday life is infinitely pleasant. This is also the main thing; the inevitable coteries are however a little tiring but I will probably get used to the idea of not being permitted to leave them when I like which is otherwise a valuable privilege for bachelors. Betty seems to like her new conditions well. She is very bright, brighter
August 1990