Hydrogenation: Major Applications

Date Published:   04/17/2020

Hydrogenation is a billion-dollar industry. Hydrogenating means to add hydrogen to something. According to Haldor Topsoe, hydrogenation comprises 48% of total hydrogen consumption, 44% of which is for hydrocracking and hydrotreating in refineries , and 4% for hydrogenation of unsaturated hydrocarbons (including hardening of edible oil) and of aromatics, hydrogenation of aldehydes and ketones (for instance oxo-products), and hydrogenation of nitrobezene (for manufacture of aniline).

 

Hydrocracking & Hydrotreating

Industrially, hydrotreating and hydrocracking are performed in down flow ‘trickle bed reactors’, where the gas and the liquid feed are sent concurrently through a fixed bed plug flow reactor. Although the flow pattern in the reactor can be reasonably approximated, the observed kinetics in such a trickle bed reactor are quite often affected by minor unplanned oscillations in the flow. How the gas and liquid collide and mix together affects the end product characteristics, so industrial reactor simulation models require that these phenomena be accounted for. Instrumentation, coupled with advance simulation software, is integrated so that operators can keep track of the mass flow of each chemical, interphase mass change, and heat transport in the trickle bed reactors.

 

Food Industry

Hydrogenated fat is usually a substitute to butter fats. High costs of butter fat and its poor storage stability led to using hydrogenated fats and oil. The unsaturated fatty acid content of triglycerides is changed by hydrogenation into hydrogenated oils by the saturating of their carbon double bonds (C=C) and converting them to single carbon bonds (C-C) in the presence of catalyst, usually Nickel. Hydrogenation accomplishes two things: 1) It increases the melting point of the oil or fat. 2) Resistance to oxidation and flavor deterioration. Hydrogenation process depends on several parameters: type of catalyst, pressure, speed of agitation, and temperature.

Unsaturated food oil is pumped in a pressure vessel called an hydrogenator. This must be equipped for good agitation, for heating and cooling, and with suitable openings for oil, hydrogen, and sampling. Vacuum is applied on the headspace and heating started. Vacuum prevents oxidation of oil when heated. Catalyst is weighed into a catalyst mix tank, slurried with a small amount of oil, and when the reaction temperature is reached the catalyst is pumped into the reactor, mixed and then hydrogen is added to the desired pressure. Hydrogenators allow the hydrogen to accumulate in the headspace above the oil with recirculation provided by vortex action of the agitator. During hydrogenation, water is circulated through the cooling coils to counteract the heat of reaction since hydrogenation is an exothermic reaction, and later for cooling prior to filtration. After cooling, the nickel catalyst is then removed from the hydrogenated fat by filtration.

 

Chemical & Pharma Synthesis

Aniline is produced by the hydrogenation of nitrobenzene. Nitrobenzene is fed with hydrogen into a tubular plug-flow reactor containing a noble metal (i.e. platinum) catalyst supported on carbon. The hydrogenation is carried out in the liquid phase.

The majority of the aniline produced globally is utilized in the manufacture of methylene diphenyl diisocyanate (MDI). To make MDI you react aniline with phosgene, in a process called Phosgenation. Phosgene is made by reacting carbon monoxide with chlorine, and like the hydrogen used in the hydrogenation process, the carbon monoxide used to make phosgene comes from a steam-methane reformer (SMR).

In the Pharma industry, the hydrogenation process is particularly useful in the production of chiral and commonly hydrogenators are used, providing organic compounds like R-3-Quinuclidinol (C7H13NO) used in the manufacture of intermediates used in APIs (activated pharmaceutical ingredients).

 

Conclusion

The hydrogenation market brings in over billions of dollars in revenue each year. For this reason, people buy and sell used hydrogenation equipment, and since this equipment is useful across multiple applications, hydrogenation equipment such as hydrogenators hold their value in the second-hand market. Please find our inventory of hydrogenators below:

 

https://www.phxequip.com/plants-subcategory.49.0/hydrogenation-plants.aspx

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