Catalyst for Increasing Octane Number in Isomerization Units
Hydrogen-Containing Unit
Three mainstream process systems, temperature parameters, and catalyst selection
✅ Catalyst: platinum supported chlorinated alumina (aluminum chloride type)
Reaction temperature: 120~175 ℃ (reactor inlet), bed temperature rise 10-25 ℃
Pressure: 2.8–3.8 MPa; liquid hourly space velocity LHSV=1.0–3.0 h⁻¹; hydrogen hydrocarbon molar ratio 0.1–0.5
Raw material requirements: strict dehydration, desulfurization, and denitrification; water/sulfur will permanently poison acidic chlorine sites; continuous chlorine supplementation is required during operation
Applicable: C₅/C₆ light naphtha, target high RON (one pass RON≈82–84, cycle up to 87–93)
Features: Highest activity, best balanced conversion rate; highly corrosive, equipped with an alkali cleaning system, complex operation and maintenance
✅Catalyst: Pt-loaded acidic molecular sieve (zeolite type, chlorine-free)
Reaction temperature: 240～280 ℃
Pressure: 2.0–3.2 MPa; LHSV=0.5–2.5 h⁻¹; hydrogen to hydrocarbon ratio 0.1–1.0
Higher raw material tolerance: sensitivity to sulfur and water is much lower than that of chlorine-aluminum catalyst, no need to supplement chlorine
Applicable: C₅/C₆, can also be used for C₄butane isomerization; the device is simpler, has good stability, and is easy to regenerate
Disadvantages: high temperature, limited equilibrium, single-pass conversion rate is lower than low-temperature aluminum chloride process, generally equipped with product fractionation + unconverted n-alkane circulation loop
✅Catalyst: Special molecular sieve/aluminum chloride system
Reaction temperature: 160–210 ℃
Pressure: 1.5–2.0 MPa; hydrogen to hydrocarbon ratio 0.07–0.15
The single-pass conversion rate is 50%–55%, and a deisobutane tower must be installed to circulate unreacted n-butane back to the reactor.
Hydrogen-Free Unit
Four major categories of hydrogen-free isomerization catalysts
Transition metal-modified acidic ZSM-5 zeolites (Zn-ZSM-5, Ga-ZSM-5, Ni-ZSM-5)
Support: ZSM-5 (MFI zeolite); Active components: Zn, Ga, Ni (non-platinum metals)
Operating conditions: 340–460°C, 0–1.2 MPa; perfectly matched to customer process requirements
Reaction characteristics: Simultaneous isomerization, aromatization, and mild cracking; increases gasoline octane number; produces propane and butane (dry gas); liquid yield of 82–90%; regeneration involves only N₂ and air for coke burn-off (no hydrogen reduction required)
Equivalent Russian grades: KT-10, KT-17, KT-18 (Zn-Ce-ZSM-Al₂O₃); hydrogen-free naphtha upgrading; gasoline octane number reaches 85–87 at 400°C
Modified mordenite (MOR) (Ni-MOR, Fe-MOR; Pt-free)
Support: Mordenite (MOR); active components: Ni/Fe (platinum-free)
Temperature range: 320–420°C; pressure: 0.3–1.0 MPa
Characteristics: Isomerization selectivity superior to ZSM-5; low aromatization activity; prone to coking at high temperatures; moderate n-alkane conversion; regeneration via air calcination (coke burn-off) only; no hydrogen required
Solid superacids (platinum-free): SO₄²⁻/ZrO₂, SO₄²⁻/TiO₂-Al₂O₃
Support: Zirconia / Titania-alumina composite oxide; no Pt loading
Temperature: 300–400°C; pressure: atmospheric to 1 MPa
Characteristics: Very high acid strength; good isomerization activity; drawbacks: sulfate groups prone to leaching at high temperatures; poor water stability; rapid coking; regeneration via air calcination only; hydrogen reduction strictly prohibited
10-ring shape-selective molecular sieves (Ni-SAPO-11, Ni-ZSM-22; platinum-free)
Support: SAPO-11 / ZSM-22; active component: Ni (no Pt)
Temperature: 330–430°C; pressure: 0.4–1.0 MPa
Characteristics: Shape-selective isomerization; high selectivity for multi-branched alkanes; drawbacks: relatively low conversion; significant gas formation due to cracking; high coking rate; regeneration via air calcination only; no hydrogen step involved.
The Field Of Petroleum Refining
Isomerization of n-butane to isobutane
Platinum-based catalysts (such as the Pt/Al₂O₃-Cl system) are used to convert n-butane into isobutane, a key feedstock for producing high-octane gasoline components (e.g., methyl tert-butyl ether, MTBE). In industrial units, mixed C4 feedstocks undergo hydro-isomerization, enabling 1-butene production capacities to reach the scale of hundreds of tons per day.
Isomerization of C5–C6 alkanes
Solid superacid catalysts (such as RISO-C or Pt/SO₄²⁻-ZrO₂-Al₂O₃) are employed to convert straight-chain alkanes into branched isomers. For instance, following the isomerization of light naphtha (from catalytic reforming), C5 and C6 isomerization rates reach 70% and 85% respectively, raising the product gasoline's Research Octane Number (RON) to above 85 and significantly optimizing fuel quality.
Aromatization Catalyst
Compared to reforming technology, this process is not limited by the potential aromatic content of the feedstock; it generally requires no pre-fractionation or refining of the raw material and offers a wide range of applicability. Feedstocks suitable for aromatic production via this process include coker gasoline, straight-run gasoline, oilfield condensate, reformer light ends (topped naphtha), reformer raffinate, pyrolysis gasoline, and olefin-rich liquefied petroleum gas (LPG).
When using olefin-rich LPG (olefin content >50%) as feedstock, the aromatic content in the liquid product approaches 100%, eliminating the need for aromatic extraction; the single-pass aromatic yield exceeds 48.2%, and the BTX yield exceeds 42.2%. The catalyst offers a single-pass operating cycle of ≥20 days and a total service life of ≥3.0 years.
When using naphtha as feedstock, the single-pass aromatic yield exceeds 35.0%, and the BTX yield exceeds 32.0%; the catalyst offers a single-pass operating cycle of 20–30 days and a total service life of ≥3.0 years.
The generated fuel gas is rich in hydrogen, which can be recovered and utilized as a hydrogen source.
Technical Features
① Relatively low aromatization reaction temperature
Advanced catalyst shaping and modification technologies enable the reaction to proceed at relatively low temperatures. In aromatic production applications, the reaction temperature is 30°C–50°C lower than that of competing technologies, significantly reducing energy consumption. Lower reaction temperatures also reduce equipment strength requirements and result in a lower dry gas yield.
② Unique reaction heat-supplementation technology
Naphtha aromatization-particularly with alkane-rich feedstocks-is a highly endothermic process. The use of unique heat-supplementation technology eliminates the need for intermediate heating furnaces, thereby reducing both capital investment and unit energy consumption.
Aromatization Catalyst for Octane Number Enhancement
Aromatization involves high-temperature dehydrogenation, cyclization, and hydrogen transfer; it is mostly conducted in the absence of added hydrogen, and operating temperatures are far higher than those for isomerization. ZSM-5 (MFI) is the predominant support, categorized into four main types based on the modifying metal:
Active component: Zn (1–3 wt%); P or rare earth elements may be added to adjust acidity and suppress coke formation.
Reaction conditions: 500–550°C, atmospheric pressure to 0.3 MPa, WHSV 0.4–1.2 h⁻¹.
Mechanism: Zn centers facilitate dehydrogenation, while zeolite acid sites catalyze cyclization; hydrogen transfer is the dominant pathway, yielding small amounts of H₂.
Suitable feedstocks: C4 liquefied gas, C5, cracked C5, light naphtha.
Commercial grades: NKC-5, DLP series, LHA type.
Characteristics: Low cost, good BTX selectivity; rapid coke formation necessitates frequent regeneration, resulting in a very short single-pass lifespan when using olefinic feedstocks.
Active component: Ga (0.5–2 wt%)
Reaction conditions: 520–580°C, atmospheric pressure
Mechanism: Ga possesses stronger dehydrogenation capability; proceeds via a direct dehydrogenation pathway, yielding more hydrogen.
Processes: BP-UOP Cyclar; domestic M2-forming
Characteristics: Higher aromatics yield compared to Zn-based catalysts; lower dry gas production; higher cost; greater sensitivity to sulfur.
Pt/Cl-Al₂O₃ (Catalytic reforming; hydrogen-rich atmosphere)
Conditions: 480–530°C, 0.8–2.0 MPa; operated in a hydrogen-rich atmosphere.
Feedstock: C6+ naphtha; produces high-octane gasoline + BTX; good resistance to coking, but requires chlorine replenishment and poses corrosion risks.
Pt/KL zeolite: Chlorine-free reforming; suitable for n-hexane aromatization; extremely sensitive to sulfur; rarely used on a large industrial scale.
⚠ Note: Catalytic reforming ≠ light hydrocarbon aromatization. Reforming operates in a hydrogen-rich atmosphere, whereas the Zn/Ga-ZSM-5 systems mentioned above are non-hydrogen-rich aromatization processes; the two systems cannot be used interchangeably. 4. Other modification systems (Mo, Ag, rare-earth composites)
Mo/HZSM-5: Methane aromatization, >700°C; suitable only for methane, not for LPG/C5.
Ag/ZSM-5: Mild dehydrogenation, moderate BTX selectivity; limited industrial application.
Rare-earth + phosphorus-modified Zn-ZSM-5: Promoter/additive rather than a standalone catalyst; used to retard coke formation and extend single-run duration (e.g., DLP-1 nano-ZSM-5).
Quick selection guide
LPG, C4/C5 feedstocks; limited budget; atmospheric pressure, non-hydrogen atmosphere → Zn/ZSM-5 (NKC-5, DLP)
Seeking higher aromatics yield and hydrogen co-production; adequate feedstock pretreatment available → Ga/ZSM-5 (Cyclar)
C6+ naphtha feedstock; hydrogen-capable unit; target product is high-octane gasoline → Pt-chlorinated alumina reforming catalyst
Methane feedstock → Mo/ZSM-5 (high temperature, >700°C)
Catalyst for Gasoline Production Via Light Hydrocarbon Aromatization
Using light hydrocarbons-such as refinery dry gas, post-etherification C4 fractions, straight-run naphtha, oilfield condensate, or coker gasoline-as feedstock, this process employs proprietary catalysts to produce high-octane gasoline blending components through steps including cracking, oligomerization, cyclization, and dehydrogenation. The resulting upgraded gasoline is characterized by low olefin and sulfur content and a high octane rating, making it an excellent clean blending component for producing automotive gasoline that meets Grade 92 and 95 standards.
Technical Features
The process utilizes a wide range of feedstocks and yields high-quality gasoline, with product schemes that can be flexibly adjusted based on market changes. The fuel gas is rich in hydrogen, which can be recovered and utilized as a hydrogen source. The industrial unit features a simple flow scheme and low investment costs, as well as low operating expenses and energy consumption.
When using olefin-rich refinery dry gas or liquefied gas as feedstock: olefin conversion >95%; gasoline selectivity for olefins >90%; gasoline octane number (RON) >92; and catalyst single-run cycle ≥45 days.
When using naphtha with low aromatic potential (such as reformate raffinate, light-end naphtha, or coal-based naphtha): gasoline octane number (RON) is 85–92; dry gas yield is 2–4%; the catalyst demonstrates strong adaptability (reducing product sulfur to <10 ppm even with a feedstock sulfur content of 300 ppm); and the single-run cycle is 30–90 days, with a total catalyst lifespan of ≥3.0 years.
Compared to similar technologies:
① The catalyst exhibits excellent activity and aromatics selectivity.
② The catalyst possesses strong resistance to coking, resulting in low dry gas yields.
③ It pioneers the use of a pressurized operation process:
---Eliminates the need for a rich-gas compressor, thereby reducing equipment costs and unit operating expenses.④ Optimized catalyst regeneration technology
---The regeneration gas-to-catalyst ratio (volume ratio of circulating gas to catalyst) is reduced by 20–30%; the regeneration section requires lower investment and operating costs while achieving high regeneration efficiency.
Olefin-Producing Catalyst
Developed in recent years, the technology for producing olefins via catalytic cracking of light hydrocarbons combines the advantages of both steam cracking and fluid catalytic cracking (FCC). It opens up a new process route that is highly significant for energy conservation and consumption reduction in petrochemical plants, as well as for meeting the growing demand for light olefins. Using feedstocks such as olefin-rich C4–C8 light hydrocarbons, straight-run naphtha, or coal-based naphtha, the technology employs a proprietary catalyst to selectively convert light hydrocarbon components into ethylene, propylene, and high-octane gasoline blending components.
Technical Features
Compared to traditional steam cracking, this catalytic cracking technology operates at lower temperatures, consumes less energy, utilizes a wider range of feedstocks, and allows for flexible product distribution. Compared to FCC-based olefin production technologies, it achieves greater cracking depth and higher yields of ethylene and propylene. Additionally, the process flow is simple, and the required investment is low.
When using C4 liquefied gas (with a butene content of ≥60%) as feedstock, the combined yield of ethylene and propylene exceeds 40%, while the gasoline yield is approximately 15–20%.