World Patent Information 31 (2009) 323–326

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Centenary patent: The catalytic converter, 1909

Stephen AdamsMagister Ltd., Crown House, 231 Kings Road, Reading RG1 4LS, United Kingdom

1 See the website of the London to Brighton Veteran Car Run, at http://

The world of patents presents a record of inventions which‘‘seemed like a good idea at the time”. In many instances, the ideais actually ahead of its time, and is never commercialised duringthe term of the patent, or indeed for decades later. One such storyis that of the catalytic converter, used for cleaning up emissionsfrom car exhausts.

Many general reference works, such as Wikipedia, Encyclopae-dia Britannica or the (US) National Inventors Hall of Fame, creditthe technical development of the catalytic converter to workersat the Engelhard Corporation in the United States, dating fromthe mid-1960s. In fact, both General Motors in the US and Volvoof Sweden arrived at a commercial solution virtually simulta-neously, around 1973–74. The first widespread use was in the USfrom 1975. The principal motivation at the time is usually ascribedto the introduction of new regulations by the US EnvironmentalProtection Agency, following the mandate of the Clean Air Exten-sion Act of 1970 ([1]). However, it is not unlikely that a secondaryfactor was the oil-price crisis of the same period, which led to in-creased intensity of research on improving vehicle fuel economy.It is clear that this period saw the first widespread commercialisa-tion of the technology, but the earliest work was from the begin-ning of the century.

In April 1909, Michel Frenkel, a Polish-born chemist resident inFrance, filed patent applications in France and the United Kingdomfor a ‘‘process and apparatus for deodorizing exhaust gases ofexplosion engines”. The French case was published on 30 Septem-ber the same year as FR 402173, (see Fig. 1) whilst the Britishequivalent was accepted in December and published as GB 9364/1909 – a prosecution time of little over 8 months for both cases,which seems almost unimaginable today for such ‘new technol-ogy’. Frenkel’s concerns about the likely impact upon air qualitydue to rapid growth in numbers of cars seem prescient, and it issomewhat surprising that there does not appear to be a US equiv-alent in the patent family, considering that the Model T Ford hadonly been launched in the United States on 1st October the previ-ous year (1908) and was to lead to a substantial increase in carownership there.

Indeed, motor transport in both Europe and the United Statesboomed during the first decade of the twentieth century. In Britainonly four years before, the Locomotives on Highways Act 1896 ([2])– otherwise known as the Emancipation Act – had repealed theinfamous controls of the Locomotives Act 1865 ([3]). This earlier

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E-mail address: stephen.adams@magister.co.uk

legislation had required all motor-driven road vehicles to have aminimum ‘‘crew” of three, of which one was required to walk 60yards ahead of the vehicle with a red flag, as a warning to othertraffic. This activity was not so hazardous to the flag-bearer asmight seem, since the same law had limited road speed to 4m.p.h. on the open road and 2 m.p.h. in towns. The removal ofthese controls is still celebrated by the ‘‘Emancipation Act” rallyof veteran cars between London and Brighton every year.1 Coinci-dent with Frenkel’s patent of 1909, the United Kingdom formed itsfirst controlling agency for road vehicles, the Road Board, whichgrew into the Ministry of Transport by 1920.

The principle of Frenkel’s invention was in many ways using thesame underlying technology as the later 1970s developments. Anoble metal catalyst – principally platinum – was loaded onto asolid support which was then mounted in a chamber inserted intothe main exhaust stream. Clearly, Frenkel understood that incom-plete combustion of fuel was a principal factor behind productionof what we would now call ‘‘particulates”, and his invention in-cluded means for diluting the exhaust stream by a secondary airblast before entering the converter chamber. This chamber couldadditionally have longitudinal fins, to improve cooling of the gasflows, and was surrounded by a ‘‘suitable sheet iron covering” toform a smooth cylinder mounted along the axis of the vehicleunderside. The general configuration of his converter can be seenin Fig. 2, a reproduction of Fig. 1 from GB 9364/1909, and the exter-nal casing (indicated by (g)) can be seen in the axial view of Fig. 3,reproduced from Fig. 3 of the same patent.

The details of Frenkel’s life are somewhat sketchy. He was bornin Warsaw in 1860 and died in Paris in 1934. It appears that he wasresident in France from around the turn of the century. In 1903 or1904, he had married the Dutch feminist novelist Cecile de Jongvan Beek en Donk (1866–1944), and they had a son, Pierre–MichelFrenkel (1905 or 1906–1972) ([4]). Frenkel senior’s dissertation(presumably doctoral) had been published in 1891 as ‘‘Beitrag zurAnalyse der Palladium-Verbindungen” (Contribution on the analysisof palladium compounds, published by Buchdruck. von C. Ströckerof Freiburg), which perhaps indicates the beginning of an interestin noble metal chemistry. He went on to publish a number ofworks2 on metal content of natural mineral and drinking waters([5–8]) and to study the physiological effects of the metal

www.lbvcr.com2 As listed in Le Catalogue collectif de France (CCFr), available via the Bibliothèque

national de France website (http://www.bnf.fr).

Fig. 1. Frenkel’s patent FR 402173.

324 S. Adams / World Patent Information 31 (2009) 323–326

Fig. 2. General longitudinal configuration of Frenkel’s converter.

Fig. 3. Axial section, showing external casing (g) around finned cylinder (b).

Fig. 4. Two alternative constructions for the catalytic support elements.

S. Adams / World Patent Information 31 (2009) 323–326 325

compounds hopogan (magnesium peroxide) and ektogan (mixedzinc and magnesium oxides and peroxides) ([9]). Clearly, his experi-ence in metallic chemistry led to a understanding of the catalyticeffects of platinum and other metals, which he exploited in his con-verter patent, following in the footsteps of Sir Humphrey Davy(1778–1829), who had first shown these properties in the early19th century.

A modern catalytic converter uses some 2–3 g of platinum.Figures for 2008 indicate that usage of platinum by the automotiveindustry is decreasing, due in part to the increased efficiency of theconverters as well as lower vehicle production ([10]). Nonetheless,some 3.1 million troy ounces (approximately 96.4 metric tonnes)of platinum was used in 2008. This represents a cost of approxi-mately US$4 bn. if world platinum prices rise as predicted toaround US$1,300 per troy ounce during 2009. Some sources

([11]) estimate that Frenkel’s converter would have used around30 g (approximately 1 troy ounce) of platinum, around 10 timesthe amount, which would clearly be unsustainable in the presentday. The Frenkel patent describes loading the catalytic componentupon a shaped solid support, in the form of either solid or hollowdiscs, not dissimilar to the ‘clay pigeons’ (skeet targets) belovedof the Edwardian shooting fraternity. The discs were perforatedalong the axis of gas flow, as shown in Fig. 4, and mounted intoslots inside the cylinder, to form a multi-stage gas exchange con-verter. The disks are marked (d) in Fig. 2, with the outer casing(b) showing the recesses into which they fitted. The design appearsalmost as if it is intended to replace individual discs, to prolong thelife of the converter, but given that the outer casing is welded, thiscould not be done in practice without destroying the device in theprocess.

Although Frenkel’s patent was examined and published in theUnited Kingdom, the final stage of acceptance, consisting of pay-ment of the sealing fee, was apparently never completed, so nopatent was actually granted. It is not clear whether the inventionwas ever put into production or incorporated into vehicles of thetime, either in the United Kingdom or France. However, it is curi-ous that there are no apparent equivalents not only in the US butalso in Germany, which at the time was an important centre ofautomotive development. Indeed, later developments grew out ofwork in the 1930s by Degea AG of Berlin who used a variety of me-tal foil structures including iron, nickel, chromium and aluminium.It is interesting to note that Degea, otherwise known as DeutscheGasglühlicht AG, are now part of MSA AUER who still manufactureemergency respirators and gas detection equipment today.

The French connection with converter technology continuesinto the post-war era, when Oxy-Catalyst Inc. of Pennsylvaniastarted to develop vehicle exhaust converters based on their estab-lished technology for cracking crude oil. This company had beenformed by Frenchman Eugene Houdry, who died in 1962, the yearthat his company’s first commercially-practical converter was pat-ented (US 3045422). Several additional patents from the samecompany in the same technical field had been granted during the1950s ([12–16]). From this decade onwards, much of the industryseems to have been driven (no pun intended) by US research,including companies such as 3M (corrugated ceramics), Corning(ceramic fibres), DuPont, Engelhard and Schneider. The acknowl-edged foundation stone patent for modern converters was grantedto Engelhard Industries in 1969 ([17]), which is the first converterto use platinum-group metals deposited on a ceramic honeycombbase. However, by stretching the definition of ‘honeycomb’ to in-clude perforated kaolin discs, Frenkel’s original work was clearlyahead of its time. Whilst some of the practical implications of hisinvention are a little alarming (such as the suggestion of ‘powderedasbestos’ as an alternative solid support), he deserves credit for ini-tiating the development of more environmentally-friendly cars.

References

[1] US Public Law 91-604, 42 USC § 7401.[2] 59 & 60 Vic. c.36.[3] 28 & 29 Vic. c.83.[4] These dates are not consistent across sources: a primary source for this paper

was the entry for Cecile in the online Biographical Dictionary of theNetherlands, <http://www.inghist.nl/Onderzoek/Projecten/BWN/lemmata/bwn5/jongvanbeek>.

[5] M. Frenkel, Analyse de la source du prieuré à Saint-Christau, exposée d’après lathéorie des sels dissociés, G. Carré and C. Naud, Paris, 1899.

[6] Veyrières F, Frenkel M, Bernard J, Pécourt A. Recherche et dosage de l’arsenicdans divers organes de moutons ayant bu pendant quatre mois de l’eau de laBourboule. Paris: La Petite imprimerie; 1900.

[7] Frenkel M. Sur le lithium dans les eaux minérales des Vosges. Paris: Impr. de G.Petit; 1904.

[8] M. Frenkel, Horo-radio-activité et débit gazeux des sources minérales. Paperpresented at the Société d’hydrologie médicale de Paris, 24 April 1911, éditionde la ‘‘Gazette des eaux”, Paris, 1911.

326 S. Adams / World Patent Information 31 (2009) 323–326

[9] Frenkel M. Nouvelle contribution à l’étude des peroxydes médicinaux,l’hopogan et l’ektogan. Paris: Bureaux du Progrès médicale; 1903.

[10] ‘Platinum 2009’, market survey by Johnson Matthey, May 2009. http://www.platinum.matthey.com/publications/Pt2009.html, (accessed 08.06.09).

[11] S. van Dulken, Inventing the 20th Century: 100 Inventions that Shaped theWorld. London: The British Library; 2000. ISBN: 0-7123-0866-0, p. 22.

[12] US 2664340, Catalytic apparatus and method for treating exhaust gases, 1953.

[13] US 2674521, Catalytic converter for exhaust gases, 1954.[14] US 2742437, Catalytic structure and composition, 1956.[15] US 2811425, Catalytic exhaust gas converter, 1957.[16] US 2898202, Gas treating apparatus, 1959.[17] US 3441381, Apparatus for purifying exhaust gases of an internal combustion

engine, 1969.