Scientists have found a new mechanism for propane dehydrogenation to help increase propylene production and efficiency

2024-10-12

Recently, tHe new energy chemical engineering team of Tianjin University has made new progress in the research on the catalytic reaction mechanism of propane dehydrogenation topropylene. By adding an appropriate amount of Hydrogen to the raw materials, the team can form more active metal hydride catalytic sites on the surface of the oxide catalyst, thereby improving the efficiency ofpropylene production. The relevant results were published in Nature Chemistry on January 2.

Propylene is an important basic chemical raw material and the basic raw material for manufacturing the "three major synthetic materials" such as plastics, synthetic rubber and synthetic fibers. Its downstream products are widely used in coatings, medicines, electrical appliances, automobiles and other fields, occupying an important position in the national economy.

Olefin production technology is an important indicator of the scientific and technological level of a country's petrochemical industry. Propane dehydrogenation is currently the second largest propylene production process in China, and it is also the new propylene production technology with the fastest market share growth and the most promising. In this technology, catalysts play an important role.

At present, the catalysts commonly used in propane dehydrogenation include platinum-based and chromium-based catalysts. Platinum-based catalysts are expensive; although chromium-based catalysts are cheap, they are toxic and suffer from "rapid coking and deactivation", requiring regeneration every ten minutes of reaction. The high temperature required for propane dehydrogenation will aggravate the coking and deactivation of the catalyst during the reaction, resulting in extremely high requirements for production equipment, which greatly limits production capacity. Therefore, suppressing coking to reduce the regeneration frequency without reducing the activity of the catalyst is of great significance for improving the efficiency of internal olefin production.

The researchers proposed a new mechanism for "metal hydride-mediated propane dehydrogenation reaction": under the reaction conditions of the presence of an appropriate amount of hydrogen in the propane feedstock, metal hydride active sites are formed on the surface of the metal oxide during the reaction. The newly generated sites participate in the propane dehydrogenation catalytic cycle, which greatly improves the intrinsic catalytic activity while inhibiting the production of coke, thus accelerating the reaction process.

Based on this, the team developed an environmentally friendly supported gallium oxide-based catalyst and a dehydrogenation process, which significantly improved the propane dehydrogenation reaction performance and was superior to international standards in terms of propane conversion rate, propylene selectivity, reaction and regeneration stability.