Catalytic reforming
Catalytic reforming is a chemical process used to convert petroleum refinery naphthas distilled from crude oil (typically having low octane ratings) into high-octane liquid products called reformates, which are premium blending stocks for high-octane gasoline. The process converts low-octane linear hydrocarbons (paraffins) into branched alkanes (isoparaffins) and cyclic naphthenes, which are then partially dehydrogenated to produce high-octane aromatic hydrocarbons. The dehydrogenation also produces significant amounts of byproduct hydrogen gas, which is fed into other refinery processes such as hydrocracking. A side reaction is hydrogenolysis, which produces light hydrocarbons of lower value, such as methane, ethane, propane and butanes.
In addition to a gasoline blending stock, reformate is the main source of aromatic bulk chemicals such as benzene, toluene, xylene and ethylbenzene which have diverse uses, most importantly as raw materials for conversion into plastics. However, the benzene content of reformate makes it carcinogenic, which has led to governmental regulations effectively requiring further processing to reduce its benzene content.
This process is quite different from and not to be confused with the catalytic steam reforming process used industrially to produce products such as hydrogen, ammonia, and methanol from natural gas, naphtha or other petroleum-derived feedstocks. Nor is this process to be confused with various other catalytic reforming processes that use methanol or biomass-derived feedstocks to produce hydrogen for fuel cells or other uses.
These are the two main classes into which the catalysts utilised for the reforming processes fall.
- Supported noble metals
- non-noble transition metal
The best catalyst for the synthesis of syngas utilising various procedures has been the subject of several research. Rhodium, ruthenium, and platinum, as well as palladium and iridium catalysts, have all been the subject of in-depth study on hydrogen production, catalytic thermal decomposition, and dry reforming catalysts. Noble metals-based catalysts are much more effective and often less susceptible to deactivation by carbon production or oxidation, but because they are more expensive (costing 100–150 times more than nickel catalysts), they are less frequently used. In industrial uses, catalysts depending on nickel are increasingly often utilised. However, due to carbon accumulation, their resilience is low. The most crucial issue for methane reforming, particularly in dry reforming, is the suppression of carbon deposition for non-noble metal catalysts. Increasing the surface basicity of catalysts and regulating the particle sizes of active ingredients are two techniques used to prevent carbon from depositing. The improvement of metal-support interaction, the creation of solid solutions, and plasma processes are only a few of the strategies that have been developed to manage the metal particle sizes. The surface basicity of catalysts was increased by using basic metal oxides as a support or promoter. Increased catalysts and processes as a consequence of the work of several authors have improved overall efficiency and environmental performance.