What do microwave popcorn, biscuits, margarine spreads, and coffee creamers have in common? Aside from making you hungry, these foods are made possible thanks to hydrogenation. We may not give a lot of thought to hydrogenation, but it’s used in everything from foods and makeup to petrochemical products.
One widely used catalyst that makes hydrogenation possible is a metallic alloy called Raney® nickel. This nickel-aluminum alloy was invented to transform cottonseed oil from a liquid into a semi-solid shortening. A series of hydrogenation experiments by chemist Murray Raney in Chattanooga, Tennessee, between 1915 and 1926 for the Chattanooga Research Company led to its discovery.1 The first patent was issued in 1925,2 with a second in 1927.3
The discovery opened the door for hydrogenation of oils, fats, and waxes in a variety of food and industrial applications. On April 7, 2022—95 years later—the American Chemical Society granted Raney nickel National Historic Chemical Landmark status.4
What Is Hydrogenation?
We commonly think of hydrogenation as a chemical process that adds texture and shelf-life to foods, but it also extends to industrial applications.
In the food industry, hydrogenation is used to solidify liquid fats fully or partially. In the petrochemical industry, hydrogenation transforms a class of unsaturated hydrocarbons called “alkenes”5—which are used to produce alcohols, plastics, lacquers, detergents, and fuels6—into saturated and less reactive forms known as “alkanes” (e.g., paraffins) and cycloalkanes (e.g., cyclic hydrocarbons, or naphthenes).7,8
The hydrogenation process involves hydrogen and another compound. Because hydrogen is generally unreactive with organic compounds, however, a catalyst is needed. Raney nickel is widely used to make a variety of catalysts for this purpose.7
What Is Raney Nickel?
In the 1920s, when Murray Raney was experimenting with nickel alloys, he patented two versions. The first version contained equal parts nickel and silicon, which was then treated with sodium hydroxide.2 His version was found to be five times more active than the existing nickel-based industry standard. Raney continued to experiment and devised a subsequent catalyst using equal parts nickel and aluminum, which forms the basis of Raney nickel catalysts still in use today.3 Promoters such as zinc, molybdenum, and chromium are also sometimes added for different uses.9
Writing in 1940, Raney noted the importance of basic research in exploring the catalytic properties of metals:
The probability that nickel or any other metal will catalyze a given reaction is based on the great amount of work that has been done in many fields, rather than on any correlated, calculable properties of either the catalyzing substance or the reacting elements or compounds. The catalytic value of a substance is determined by trial; if it does its work, it is good.10
Since his original catalysts were devised, the world has bent Raney’s discovery to a vast array of uses. At the broadest level, Raney nickel is used today as a catalyst to help convert building-block chemicals into pharmaceuticals, food ingredients, personal care products, agrochemicals, and petroleum processing.4,11 Today, W. R. Grace & Co produces a variety of catalysts for hydrogenation and dehydrogenation using Raney nickel.
Since its discovery, Raney nickel has been used in a variety of oxidative and reductive applications including:
- Desulfurization of benzonaphthothiophenes and dibenzothiophene
- The catalytic hydrogenation of 2,3,5-trimethylbenzoquinone (TMBQ) to 2,3,5-trimethylhydroquinone (TMHQ)
- Use in combination with palladium to catalyze the methanolysis of borane-amine adducts
- The conversion of crude palm oil into hydrocarbons, hydrocracking organosolv lignin to phenols
- Deoxygenation of alcohols
Novel uses of Raney Nickel
Today, new uses are being explored for Raney nickel. One application is in the emerging field of biomass conversion, where it is used as a catalyst to upgrade raw biomass into biofuels.12,13 With the admirable goal of weaning the world off fossil fuels, this use of Raney nickel may prove to be its most valuable contribution yet. Another use is as a catalyst for hydrogenation to synthesize cariprazine, an anti-psychotic drug used in the treatment of schizophrenia.14
- The Discoverer of Raney Nickel. Raymond B. Seymour. Chemical and Engineering News Archive, 1947, 25 (37), p 2628. DOI:10.1021/cen-v025n037
- Method of Preparing Catalytic Material [US Patent Application]. Murray Raney. 1924, https://patents.google.com/patent/US1563587A/en
- Method of Producing Finely-Divided Nickel [US Patent Application]. Murray Raney. May 10, 1927, https://patentimages.storage.googleapis.com/30/af/21/aca0026193570c/US1628190.pdf
- Development of Raney Nickel Catalyst Earns Historic Chemical Landmark Designation [Press Release]. American Chemical Society. April 6, 2022, https://www.acs.org/content/acs/en/pressroom/newsreleases/2022/april/development-of-raney-nickel-catalyst-earns-historic-chemical-landmark-designation.html
- Alkenes. LibreTexts Chemistry. Updated September 13, 2020, https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Alkenes
- Alkenes. ByJu’s. Accessed April 14, 2022, https://byjus.com/chemistry/alkene/
- Hydrogenation: Catalysts. Wikipedia. Updated February 8, 2022, https://en.wikipedia.org/wiki/Hydrogenation#Catalysts
- Naphthenes. ScienceDirect. Accessed April 14, 2022, https://www.sciencedirect.com/topics/engineering/naphthenes
- Raney Nickel. Wikipedia. Updated December 21, 2021, https://en.wikipedia.org/wiki/Raney_nickel
- Catalysts from Alloys. Murray Raney. Industrial and Engineering Chemistry, 1940, 32 (9), pp 1199–1203. DOI: 10.1021/ie50369a030
- Chemical Processing. GRACE. Accessed April 14, 2022, https://grace.com/industries/chemical-processing
- Raney Ni as a Versatile Catalyst for Biomass Conversion. Zhouhua Sun, Zhe-Hui Zhang, Tong-Qi Yuan, Xiaohong Ren, and Zeming Rong. ACS Catalysis, 2021, 11 (16), pp 10508–10536. DOI: 10.1021/acscatal.1c02433
- Advances and Challenges in the Valorization of Bio-Oil: Hydrodeoxygenation Using Carbon-Supported Catalysts. Tomás Cordero-Lanzac, José Rodríguez-Mirasol, Tomás Cordero, and Javier Bilbao. Energy Fuels, 2021, 35 (21), pp 17008–17031. DOI: 10.1021/acs.energyfuels.1c01700
- Review of Synthetic Approaches toward the Synthesis of Cariprazine, an Antipsychotic Drug. Siddhanath D. Bhosle, Shivanand V. Image, Balraju Gangapuram, Gyanchander Eppa, RRajesh S. Bhossal, and Jhillu Singh Yadav. Org. Process Res. Dev, 2022, 26 (3) 493-507. DOI: 10.1021/acs.oprd.1c00488