From the hardening of vegetable oil, the hydrodesulfurization, to the enantioselective reduction to produce a pharmaceutical active ingredient, all these processes use a catalyst to add molecular hydrogen to a reactive, unsaturated fragment (such as C=C, C=O or C=N) of a target molecule. Catalytic hydrogenation is one of the most widespread reaction practiced throughout the chemical industry. The first steps toward the industrial hydrogenation were made in 1897 by the French chemist Sabatier who was later awarded the Nobel Prize in Chemistry in 1912 “for his method of hydrogenating organic compounds in the presence of finely disintegrated metals”. Since the initial discovery by Sabatier, the hydrogenation technology has greatly developed to improve the activity, selectivity and catalyst stability.
The development of catalytic hydrogenation reactions is an outstanding example of how chemical research influences industry practices. Evidenced by the large number of patents filed nowadays, catalytic hydrogenation reactions are practiced extensively and the filed patents are thus an important indicator of technological evolution. In this light, a very interesting overview on the patent landscape in the area of hydrogenation reactions was recently published in advanced synthesis and catalysisby Glorius, Leker and coworkers (DOI: 10.1002/adsc.201901292). The authors explore the different patent classes and sub classes and order the information according to the type of catalyst (heterogeneous versus homogeneous catalysts), active metal, support, ligand, catalyst preparation and geographic filing location (just to name a few). All these data paint a very informative picture of the current status of the technology and the research activities in different parts of the world.
The first observation made by the authors is that the field of hydrogenation catalysis is still growing and reaches a stage where the competitive impact is high. The heterogeneous catalysts patents outnumber the homogeneous catalysts. The annual growth rate of the heterogeneous hydrogenation is twice as high as the number of patent families in homogeneous hydrogenation. The authors ascribe this to the industrial applicability of heterogeneous catalysts by (relatively) ease of separation and re-use of precious metal catalysts.
For the heterogeneous catalysts, palladium which is the “working horse” in hydrogenation technology remains in the top position of most patented metal (1753 patent families between 2011-2015). The growth rate (of filed patent families) of 3.8% over 2011-2015 puts palladium in a medium growth range. The second most patented metal among hydrogenation catalysts is nickel. Interestingly, the highest annual growth rates of filed patents were observed for iron, nickel and cobalt (9.4%, 7.1% and 6.6 %, respectively). This show the industrial importance and increasing interest in these first-row metals as a heterogeneous catalyst and potential substitute for the more expensive precious metal containing catalysts.
Sorting the type of metals of the catalysts by geographical region reveals interesting trends. For nickel, the highest number of patent families was registered in China as a priority country (34% of all patent families), followed by Europe (28%), the USA (16%), and Japan (11%). Similar trends were observed for other first-row transition metals such iron, cobalt and copper. These trends show the increasing relevance of China as a catalyst market and hydrogenation technology innovator.
The homogeneous catalyst patent landscape shows that rhodium is still the most patented transition metal as it is one of the most studied class of catalysts in the field of homogeneous catalysis. The asymmetric hydrogenation process for the enantioselective production of L-DOPA which was patented by Monsanto in 1970s remains one of the textbook examples. Ruthenium, found as the active metal in Noyori-type catalysts, is also found in great abundance in the patent literature and displays the largest annual growth rate (3.4%). Although the use of base metals would also be highly desirable in homogenous catalysis, and technologies are emerging in this field, the shift towards the use of base metals that was observed in heterogeneous catalysis was not found in the patent landscape of homogeneous catalysis. For homogeneous catalysts, a higher patenting activity was found in Europe, the USA and Japan.
Finally, for evaluating the economic value of the patents the authors use the triadic patents as indicator. Triadic patents are patents that are registered in three strong economies (USA, EU and Japan), and therefore must be of high industrial relevance. The highest shares of triadic patent families among the homogeneous catalysts were registered for ruthenium (50%), iridium (48%), and palladium (47%). The heterogeneous catalysts display a much lower share of triadic patents (highest share was found for “for ruthenium, rhodium, osmium and iridium”, 38%). The authors state that the structure of a homogeneous complex can often be identified and reproduced much more easily than the back-engineering of a heterogeneous catalyst. Thus, protecting a homogeneous catalyst technology requires a more elaborate patent strategy.
This article represents a closer look to the activity and dynamics in the hydrogenation technology field. We believe that such analysis would be very helpful for other catalytic technologies such as cross-coupling technologies and hydroformylation.
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