| 1 | Fluid Catalytic Cracking (FCC) Zeolite Catalyst | Fluid catalytic cracking | Y-type zeolite, usually stabilized or ultrastable, dispersed in a silica–alumina matrix | Cracks vacuum gas oil into lighter hydrocarbons through strong acid sites | Approximately 480–550 °C reactor temperature; near-atmospheric to moderately elevated pressure | Vacuum gas oil, heavy gas oil, and selected residue streams | High yields of gasoline-range hydrocarbons, LPG, and light olefins | Catalyst activity, bottoms conversion, coke selectivity, metals tolerance, attrition resistance, and zeolite-to-matrix balance |
| 2 | Cobalt–Molybdenum Hydrotreating Catalyst | Diesel and naphtha hydrotreating | Molybdenum sulfide promoted with cobalt on porous alumina | Hydrodesulfurization and moderate hydrodenitrogenation | Approximately 280–380 °C; commonly 20–80 bar hydrogen pressure | Straight-run naphtha, kerosene, diesel, and gas oils | Lower sulfur fuels and improved fuel stability | Sulfur and nitrogen level, feed boiling range, hydrogen consumption, pressure drop, and tolerance to contaminants |
| 3 | Nickel–Molybdenum Hydrotreating Catalyst | Hydrodesulfurization and hydrodenitrogenation | Molybdenum sulfide promoted with nickel on alumina or a silica–alumina support | Deep removal of sulfur and nitrogen; improved hydrogenation of aromatic compounds | Approximately 300–420 °C; commonly 30–130 bar hydrogen pressure | Heavy gas oil, coker gas oil, vacuum gas oil, and residue-derived feeds | Ultra-low-sulfur feed or product and reduced nitrogen inhibition in downstream units | Hydrogen partial pressure, aromatic saturation requirement, metals deposition, pore-size distribution, and catalyst cycle length |
| 4 | Nickel–Tungsten Hydrocracking Catalyst | Hydrocracking | Nickel–tungsten sulfide hydrogenation function combined with acidic zeolite or amorphous silica–alumina | Converts heavy molecules while simultaneously hydrogenating and removing heteroatoms | Approximately 350–430 °C; commonly 80–200 bar hydrogen pressure | Vacuum gas oil and hydrotreated heavy distillates | High-quality diesel, kerosene, naphtha, and lubricant-range products | Conversion target, product selectivity, hydrogen consumption, acidity, feed nitrogen, and resistance to deactivation |
| 5 | Platinum–Rhenium Reforming Catalyst | Catalytic reforming | Platinum and rhenium on chlorided alumina | Dehydrogenation, isomerization, and dehydrocyclization of naphthenes and paraffins | Approximately 450–540 °C; typically 5–35 bar hydrogen-containing process gas | Hydrotreated heavy naphtha | High-octane reformate and valuable hydrogen by-product | Chloride and moisture control, coke resistance, platinum dispersion, regeneration method, and reformate octane target |
| 6 | Isomerization Catalyst | Light naphtha isomerization | Platinum on chlorided alumina or platinum on sulfated zirconia | Rearranges normal pentane and hexane into branched isomers | Approximately 120–250 °C, depending on catalyst family; hydrogen is normally present | C5/C6 light naphtha with low sulfur and low water content | Higher octane without significant aromatic or olefin formation | Feed dryness, sulfur removal, benzene management, equilibrium limitations, and sensitivity to contaminants |
| 7 | Solid Acid Alkylation Catalyst | Isobutane–olefin alkylation | Strong solid acids such as ion-exchanged zeolites or supported superacid systems | Combines light olefins with isobutane to form branched paraffins | Generally low to moderate temperature; the exact window depends strongly on the solid-acid technology | Propylene, butylenes, amylenes, and isobutane | Low-sulfur, low-olefin, high-octane alkylate blending component | Acid strength, catalyst regeneration, water tolerance, olefin-to-isobutane ratio, corrosion control, and product selectivity |
| 8 | Residue Hydroprocessing Catalyst | Fixed-bed, moving-bed, or ebullated-bed residue upgrading | Nickel–molybdenum or nickel–tungsten sulfides on graded porous supports | Removes sulfur, nitrogen, metals, and Conradson carbon while increasing hydrogen content | Approximately 350–450 °C; commonly 100–200 bar hydrogen pressure | Atmospheric residue, vacuum residue, and deasphalted oil | Cleaner refinery feed, reduced fuel-oil sulfur, and improved downstream conversion | Vanadium and nickel tolerance, pore-mouth plugging, metals capacity, guard-bed design, and replacement frequency |
| 9 | Selective Hydrogenation Catalyst | Naphtha, pygas, or FCC gasoline hydrogenation | Palladium, nickel, or supported noble-metal formulations selected for controlled hydrogenation | Saturates unstable diolefins and acetylenes while limiting excessive olefin conversion | Approximately 40–220 °C, depending on feed and target reaction; low to moderate hydrogen pressure | Pyrolysis gasoline, FCC gasoline, and olefin-rich refinery streams | Improved product stability, reduced gum formation, and controlled sulfur or olefin management | Selectivity, feed contaminants, temperature rise, hydrogen-to-feed ratio, pressure drop, and protection against over-hydrogenation |
| 10 | Claus Sulfur-Recovery Catalyst | Sulfur recovery from acid gas | High-surface-area activated alumina, often supplemented with titania for enhanced hydrolysis or sulfur conversion | Promotes conversion of hydrogen sulfide and sulfur dioxide into elemental sulfur | Approximately 200–350 °C in catalytic Claus converters | Amine-acid gas and sour-water-stripper gas containing hydrogen sulfide | Higher sulfur recovery, lower sulfur emissions, and improved compliance with environmental limits | Thermal stability, water and hydrocarbon tolerance, COS/CS2 hydrolysis activity, fouling resistance, and pressure drop |