The Pivotal Role of Platinum in the Discovery of Catalysis THE PIONEERING WORK OF JOHANN WOLFGANG DOBEREINER DURING THE 1820s By P. M. D. Collins Science and Engineering Policy Studies Unit, The Royal Society, London

By the early years of the nineteenth century taken up in Germany by Dobereiner, whose the more important physical properties of thorough investigation of the effect of platinum platinum had become reasonably well under- on hydrogen was the key to the discovery of the stood and had formed the basis of several dif- phenomenon of catalysis. ferent applications, but one of its major Johann Wolfgang Dobereher was born in properties-its remarkable function as a 1780 in Hof an der Saale, a town some 40 miles catalyst-was yet to be discovered. Tentative north of Bayreuth. Originally intended for a reports of its effect in the oxidation of methane career in estate management, he contrived to and of alcohol had been made by both Hum- obtain sufficient tutoring to become appren- phry Davy and his cousin Edmund, but neither ticed instead to a local apothecary at the age of of them sought to interpret their findings in any 14. His three-year apprenticeship completed, detail. However, the subject was vigorously he set off on a five-year journey which included

Johann Wolfgang Dobereiner 1780- 1849 Professor of Chemistry at Jena for thirty-nine years, a friend and prot6g6 of Goethe, and the founder of the study of catalysis, his discovery of the power of finely divided platinum to ignite a stream of hydrogen caused a con- siderable stir in European chemical circles

From P ponrut in the pormrion of Gathc Nnrronnlmuvum der Natiorulc Forvhungr und Gedenkst4trcn. Wemar

Platinum Metals Rev., 1986, 30, (3), 141-146 141 periods of thorough if unofficial study of expense, ran courses in practical experimental chemistry and mineralogy at Karlsruhe and chemistry some years before Liebig’s more Strasbourg. A succession of pharmaceutical and famous courses at Giessen. Secondly, during technological jobs followed, each enhancing his the 1820s he developed his theory of “triads”, scientific experience and reputation but none an early pointer towards the Periodic Table. affording much financial security. Indeed, by And thirdly there was his important pioneering I 8 10he found himself unemployed, in debt and work on platinum catalysis. with a sizeable family to support. From this predicament he was rescued by the Earlier Experiments with Platinum offer of the chair of chemistry and technology The precursor to Dobereiner’s work on plati- at Jena University. Jena lay in the State of Saxe- num is to be found in Humphry Davy’s re- Weimar, whose ruler, Duke Carl August, was searches related to the miner’s safety lamp. an enlightened patron of both the arts and Davy discovered that a spiral of platinum wire science. He was keenly aware of the practical in the vicinity of an ignited wick in the lamp value of science for his State, and when seeking would catalyse the continued oxidation of coal an occupant for the chair specified a man of gas (methane) with sufficient vigour to glow “scientific genius with practical flair”. This white hot after the wick was extinguished. At outlook found a sympathetic response in least, that is how one would now describe his Dobereiner. In addition to his official duties as experiment; but Davy’s central concern at the a professor he served as an impromptu consul- time was with the nature of combustion and tant on a wide range of issues, added to his safety in mines. He recognised that the addition portfolio the post of Inspector of Mines and in of the platinum spiral was a useful modification 1820 was appointed Privy Councillor. Ever the to the miner’s lamp, but of the phenomenon he practical man, Dobereiner directed in his will had observed, he simply remarked that it was that his body be buried with no coffin and that “more like magic than anything I have seen two fruit trees be planted on the grave, “so that . . . it depends upon a perfectly new principle the products of the decay of my corpse may in combustion” (I). turn into organic matter and appear in another Humphry’s cousin Edmund Davy, working guise in new life”. at the Cork Institution, was then carrying out a Carl August had brought Goethe to Weimar series of researches on the Chemistry of in 1775 and a close relationship grew up be- platinum. In the course of this he found that tween the three men. Carl August and Goethe platinum sulphate could be reduced by alcohol provided Diibereiner with the best facilities to platinum in finely divided form. The that the State could afford; DBbereiner for his platinum powder, Davy observed, reacted part stayed at Jena for the rest of his life despite strongly with alcohol vapour at room tem- offers of more lucrative and prestigious chairs perature, remaining white hot until all the as his reputation grew. Carl August became alcohol was consumed. “This mode of igniting godfather to two of Dobereiner’s children and metal”, he remarked, “seems to be quite a new Goethe to one. Goethe once wrote a poem for fact in the history of chemistry; but the means Dobereiner when he was ill, and another of his of keeping it in a state of ignition is only poems prefaced Dobereiner’s book on his another illustration of the facts previously platinum research. After Dobereiner’s death in pointed out by Sir H Davy” (2). 1849 the town of Jena erected a statue to his Edmund Davy’s paper was published in Ger- memory. man translation in 1821, and Dijbereiner Apart from his wide-ranging work in applied promptly set about repeating his experiments. chemistry, Diibereiner’s reputation now rests The context, however, was crucially different. on three aspects of his career. He was a very Dobereiner was then concerned with the successful teacher and, at considerable personal chemistry not of platinum but of alcohol, so he

Platinum Merals Rev., 1986, 30, (3) 142 Dobereiner began his career as Professor of Chemistry in rooms in the palace of hie patron, Duke Carl August of Saxe-Weimar-Eisenach,but these soon proved inadequate and in 1816 a large house was acquired, shown on the right of this illustration, for use as both a laboratory and a home. Later, in 1833, a new laboratory, visible behind the trees, was built for him to plans drawn up by the Duke’s Minister of State. Goethe emphasised not so much the glowing of the Davy’s platinum powder on alcohol. He con- platinum powder as its ability to induce the oxi- tinued to work on the properties of that powder dation of alcohol to acetic acid. He explained during the winter, investigating also the pro- this ability in terms of the platinum electro- perties of a form of finely divided platinum pro- chemically activating the alcohol towards re- duced by ignition of ammonium chloroplatinate action with oxygen. He also noted that the and extending the range of gases and vapours platinum was not used up by the reaction but studied to include hydrogen. could “be used again to acidify fresh, perhaps limitless, quantities of alcohol;-a circumstance The Crucial Experiments which permits its use for the large-scale The experiments that finally caught the im- preparation of acetic acid” (3). In the event, agination of the scientific world were carried Dobereiner did get as far as designing an out in the summer of 1823. On the 27th July “Essiglampe”, but did not exploit the reaction Dobereiner prepared some platinum powder by commercially. ignition of ammonium chloroplatinate and ex- Dobereiner published his results in 1822. He posed it to hydrogen. As he had expected, spent the Christmas of that year with Goethe in nothing happened. He then admitted some air Weimar and, among other experiments, to the hydrogen, and “there now followed in a demonstrated to him the action of Edmund few moments that strange reaction: the volume

Platinum Metals Rev., 1986, 30, (3) 143 of the gases diminished and after ten minutes Dobereiner’s work caused “a great sensation all the oxygen in the admitted air had condens- and excited the liveliest interest” in Paris, ed with the hydrogen to water” (4). Substitu- according to Liebig who was studying there at tion of pure oxygen for the air made the the time. It was reported in the dailyJourna1 des reaction vigorous enough to char the filter dkbats on 24th August, the article concluding: paper holding the platinum powder. “This beautiful discovery is going to open a Dobereiner was so taken by these ex- new field of research in physics and chemistry” periments that he repeated them “at least thirty (7). The French chemists Thenard and times” that day, and “always with the same Dulong, who had earlier investigated the de- result”. He proposed a mechanism analogous composition of ammonia by heated metals and to that used in his 1821 experiments on the oxi- of hydrogen peroxide, immediately set to work; dation of alcohol: “The entire phenomenon by 15th September they were able to present to must be regarded as an electrical one, whereby the Academie des Sciences a paper extending the hydrogen forms an electrical chain with the Dobereiner’s work to other forms of platinum platinum”. He promptly dashed off an account and to other metals (8). Further papers fol- of his work to Goethe and to the editors of three lowed, but the nature of the phenomenon re- scientific journals; it was published a month mained obscure. On 29th November Liebig later (a speed of publication that modern infor- wrote to Dobereiner that, at a dinner for a mation technology seems unable to match). group of leading scientists, “your beautiful and On 3rd August Diibereiner produced an even as yet inexplicable discovery was discussed in more striking version of his experiment. In- the most glowing terms”. The same letter ex- stead of the previous static arrangement, he pressed strong, if tactful, reservations about directed a fine jet of hydrogen at the platinum Dobereiner’s initially proposed mechanism. from a distance of 4 cm, so that it was mixed News of D6bereiner’s work reached England with air before reaching its target. This had the via a letter from the French chemist J. N. P. effect of making the platinum immediately Hachette to Michael Faraday (9). Before the white hot and igniting the hydrogen jet. More end of September Faraday had repeated the ex- excited letters were dispatched, commenting periment and, in his laboratory notebook, had that “this experiment is most surprising and ascribed the phenomenon to the adsorptive amazes every observer when one tells him that powers of the divided platinum (10). At that it is the result of a dynamic interaction between time he was unable to pursue his investigations two types of matter, one of which is the lightest further, but he returned to the subject with and the other the heaviest of all known bodies” great effect ten years later. Other English (4). chemists also carried out experiments on the Seven weeks later Dobereiner demonstrated phenomenon. his experiments to the meeting in Halle of the Gesellschaft deutscher Naturforscher und Commendation of Dobereiner’s he.By then he was less confident of the Work by Jons Jacob Berzelius mechanism he had first proposed: “Most likely Dobereiner’s experiments, then, provoked a a new natural principle is operative here, which great deal of interest and prompted many will become apparent through fufzher investi- chemists in different countries to carry out hr- gation” (5). In a small book published in Oc- ther investigations. This was reflected in the tober 1823 and dedicated to Carl August, in summary of the year’s events prepared by the which he summarised his summer’s experi- Swedish chemist Berzelius. In 1821 Benelius ments, Dobereiner suggested that the had taken upon himself the monumental task of mechanism was “probably of a quite special reviewing the advances of physical science dur- nature, i.e. neither mechanical nor electrical ing the previous year and presenting them nor magnetic” (6). in a series of annual reports. These owed their

Platinum Metals Rev., 1986, 30, (3) 144 An incidental result of Dobereiner’s discoveries was his invention of the first lighter. This employed hydrogen, generated from zinc and sulphuric acid, passing over finely divided platinum which then glowed sdEciently to ignite the gas. A number of different types produced in Germany and in England became very popular and many thousands of them were in use over a long period of time. Many elaborate and fanciful designs on enamel or porcelain were also developed including the two models illuetrated here Gunmy of ihc Danish Naiiannt Museum siderable influence to the fact that they were Dobereiner we were sceptical of it; it is, also published in German translation, initially nonetheless, true” (13). by C. G. Gmelin and then by Friedrich Wohler. When writing his review of 1835, Benelius When he came to assessing 1823, Benelius was able to reflect on a wide variety of ex- wrote: “From any point of view the most im- perimental and theoretical researches that had portant and, if I may use the expression, the what he realised was a simple phenomenon in most brilliant discovery of last year is, without common. He gave to that phenomenon the doubt, that . . . made by Dijbereiner” (11). name “catalysis”, stressing as he did so that the The warmth of this appraisal becomes all the name was intended to identify a particular greater when one considers Benelius’ earlier phenomenon rather than to provide a single ex- low opinion of Diibereiner. In July 1821 he had planation (operation of a “catalytic force”) for commented to Gaspard de la Rive, professor of all instances of that phenomenon. chemistry in Geneva, “I do not know whether he (Thomas Thomson) or Dobereiner in Ger- The First Practical Applications many is the worst chemist in existence at the Dijbereiner immediately turned his discovery moment” (12). On 30th October 1823, how- to practical ends. Already on 5th August 1823, ever de la Rive found himself grudgingly writ- he wrote, “I have already used this latest obser- ing to Benelius: “We have had nothing new vation to construct a new lighter and a new here since Dobereiner’s experiment with his lamp, and shall apply it to far more important platinum; in view of the reputation of the said ends” (14). One of those ends was eudiometry:

Platinum Metals Rev., 1986, 30, (3) 145 he was able to demonstrate its value in By 1828 some 20,000 Dobereiner lighters were eudiometry at the Halle conference, and in use in England and Germany alone, and it Michael Faraday was using it routinely for this eventually found its way into most European purpose by the end of the year. He also used countries. In spite of the invention of the safety platinum to prepare sulphuric acid by catalytic match in 1848 by one of his former students, R. oxidation of sulphur dioxide to sulphur triox- C. Mttger, the Dabereiner lighter was still in ide, independently of Peregrine Phillips who use at the beginning of the First World War. patented the process in England in 1831, but he Part of its attraction lay in the scope it offered did not establish the technique on a large scale. to the imaginative decorator: Dobereiner Indeed, the application most associated with himself suggested that one could “embellish it Dobereiner is the lighter. Like Humphry Davy with two alchemical symbols, namely the lion with his safety lamp, Dobereiner refused to and the snake, and so arrange it that the snake patent his invention, published all the designs takes the place of the capillary tube for the and spumed a large offer from an Englishman stream of hydrogen and the open jaws of the named Robinson for monopoly rights with the lion sitting opposite the snake hold the words “I love science more than money” (14). platinum” (I5).

References I Letter from Davy to John Buddle, British 8 P. L. Dulong and L. J. Thenard, Ann. Chim., Museum Add. MSS 33963 f. 1x4 1823, 23, 440-443 2 E. Davy, Phil. Trans. Roy. SOC., 1820, 1x0, 9 Letter from J. N. P. Hachette to Faraday, 16th 108-125 September 1823, I.E.E. Archives 3 J. W. Dabereiner, Ann. Ph.ys. (Gilbert), 1822, 72, 10 M. Faraday, Royal Institution Laboratory 193-198 Notebook No. 8, 81 4 J. W. Wbereiner, 3. fur Chem. (Schweigger), I I J.J. Berzelius,Jahres-Bericht,1823/1825,4,60-61 1823, 38, 321-326; Ann. Phys. (Gilbert), 1823, 12 H. G. Siiderbaum, Jac. Berzelius Bref, Uppsala, 74, 269-273 1912-1935, 3, letter of 23rd July 1821 5 J. W. Wbereiner, J. fir Chem. (Schweigger), 13 Ibid, letter of 30th October 1823 1823, 39, 1-16 14 W. Prandtl, Deutscher Chemiker in der ersten 6 J. W. Wbereiner, Uber neu entdecke hlichst Hdfte des neunzehnten Jahrhunderts, Wein- merkwiirdige Eigenschaften des Platins, Jena, heh, 1956, P. 49 1823 15 J. W. Wbereiner, Zur Chemie des Platins, Stutt- 7 J. des dibats, 1823, 24th August gan, 1836, P. 76

Platinum 1986 A year ago Johnson Matthey published previous year, when the supply of primary “Platinum 1985”, the first of a new series platinum increased from 2,470,000 oz in of annual surveys of the world of platinum 1984 to 2,510,000 oz, and in the same and the other five metals of the platinum period demand in the Western World in- group. This was designed to complement creased from 2,630,000 to 2,810,000. As Platinum Metals Review by providing a the first of a series of occasional articles on comprehensive survey of the commercial topical subjects it includes a four aspects df these metals, including their page survey on fuel cells as a potential supply and demand, international source of electrical power and as a major markets, major applications and related outlet for platinum. aspects, with supporting statistical data. Copies of “Platinum 1986” may be ob- The second of these annual reviews, tained from Mr. G. G. Robson, Johnson “Platinum 1986”, has now been publish- Matthey P.L.C., New Garden House, 78 ed. This concentrates on the events of the Hatton Garden, London ECIN 8JP.

Platinum Metals Rev., 1986, 30, (3) 146