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| HS Code | 805290 |
| Appearance | Pale yellow to dark brown oily liquid |
| Physical State | Liquid |
| Odor | Strong aromatic, naphthalene-like odor |
| Density | 0.98 - 1.05 g/cm³ at 20°C |
| Viscosity | 1.5 - 3.0 mPa·s at 40°C |
| Boiling Range | 210 - 320°C |
| Flash Point | Approximately 105°C (closed cup) |
| Autoignition Temperature | Approximately 480°C |
| Vapor Pressure | Less than 0.1 kPa at 20°C |
| Solubility In Water | Insoluble |
| Aromatic Content | Greater than 90 wt% |
| Average Molecular Weight | Approximately 130 - 180 g/mol |
As an accredited Cracking Naphthalene Fraction factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Cracking Naphthalene Fraction supplied in 200-litre steel drums, securely sealed with hazard labelling and safety documentation for transport. |
| Container Loading (20′ FCL) | Cracking Naphthalene Fraction is packed in approved drums/IBCs and loaded as a 20′ FCL, securely stowed. |
| Shipping | Cracking Naphthalene Fraction is typically shipped as a flammable liquid in dedicated tankers, drums, or isotanks. Ensure proper UN classification, hazard labeling, and documentation. Use grounded equipment, avoid ignition sources, and provide secondary containment. Ventilation is essential; personnel must handle with PPE per safety data sheet regulations. |
| Storage | Store in tightly sealed, corrosion-resistant containers in a cool, dry, well-ventilated area, away from heat, open flames, sparks, and incompatible oxidizers. Use explosion-proof electrical equipment and bond containers to prevent static discharge. Protect from physical damage and sunlight. Keep spills contained, comply with environmental regulations, and ensure clear hazardous material labeling. |
| Shelf Life | Shelf life is typically 12 months when stored in sealed containers away from heat, ignition sources, and sunlight. |
C10+ cracking naphthalene fraction collected from ethylene plant quench oil distillation is handled as a multicomponent aromatic stock rather than a single-component feedstock. The atmospheric boiling interval of 210°C to 260°C concentrates naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, biphenyl, acenaphthene, indene and minor alkylbenzenes. Because naphthalene solidifies at 80.2°C but the methylnaphthalenes depress the crystalliser feed freezing point to 60–75°C depending on assay, static or falling-film crystallisers are operated with slow cooling ramps of 1–3°C/h to prevent occluded impurity pockets. The recovery route produces technical-grade naphthalene for subsequent derivative plants; a salable crystal purity of 98.0–99.5 wt% is typical when sweating at 80–82°C is used to purge low-melting alkyl aromatics. Distillation-only recovery is less effective because close-boiling biphenyl and α-methylnaphthalene co-distil with naphthalene; thermal stressing in reboilers above 220°C can initiate polymer formation that fouls structured packing and reduces run length. Compliance for export batches commonly cites GC-FID naphthalene content, ASTM D4052 density at 15°C, ASTM D95 water content and solidification point measured by ASTM D1493. A representative downstream quality gate is shown in Table 1.
| Downstream route | Key parameter | Typical specification window |
|---|---|---|
| Refined naphthalene crystallisation | Naphthalene GC-FID area % | 60–85 |
| Phthalic anhydride feedstock | Methylnaphthalene GC-FID area % | <10 |
| Concrete admixture sulfonation | Indene content GC-FID | <0.5 |
| Carbon black feedstock blending | Density at 15°C, ASTM D4052 | 1.06–1.14 g/cm³ |
In fixed-bed phthalic anhydride production, recovered naphthalene from cracked C10–C12 material is evaporated into a preheated air stream at typical loadings of 45–60 g/Nm³ and fed to multi-tubular reactors containing a vanadium pentoxide–potassium sulfate catalyst supported on anatase-TiO2. The heat-transfer fluid is circulated at 340–370°C through the shell side; exothermic selectivity shift at hot spots above 430°C promotes maleic anhydride and naphthoquinone formation. Since methylnaphthalenes in the raw cracked fraction have higher reaction heats per mole than naphthalene, their presence at more than 10 area% can force a reduction in feed loading to maintain hot-spot temperature under 430°C. The process gas leaving the reactor is cooled in switch condensers, where solid phthalic anhydride is desublimated at 105–135°C and later melted for transfer. Distillation of crude phthalic anhydride removes low boilers and tar; export specifications are typically tested by ISO 1389-1:1997 methods for colour, solidification point and maleic anhydride content. Published data for the exact yield penalty of cracked C10 versus coal tar naphthalene in Chinese fixed-bed units is limited; however, plant audits attribute shortened catalyst cycles to elevated acenaphthene and indene when naphthalene fraction is not pre-treated.
The manufacture of naphthalene-based high-range water reducers from cracked C10 material begins with sulfonation of the naphthalene-rich cut using 98% sulfuric acid or 25% oleum at 155–165°C, applying a naphthalene-to-sulfuric acid molar ratio between 1:1.3 and 1:1.8. The sulfonation mass is hydrolysed with water or dilute acid at 140–155°C to destroy α-isomer and sulfone by-products; formaldehyde is then charged at 0.9–1.0 mol per mol of naphthalene at 95–110°C to build the β-naphthalenesulfonate-formaldehyde condensate. Caustic soda or sodium carbonate neutralisation to pH 8–10 yields a 38–42% solids solution or spray-dried powder with bulk density 0.6–0.8 g/cm³. The polymeric product is tested as a Type F or Type G high-range water reducer under ASTM C494/C494M-19; EN 934-2 Table 3.1 is used for CE-marked admixtures. Normal concrete dosages are 0.5–1.2% by mass of cementitious binder, adjusted in mix designs where polycarboxylate ether competition changes adsorption behaviour. Production line observations show that unsaturated impurities such as indene present in cracked C10 feed increase colour body formation in the condensate; if the sulfonated product is not washed, the final powder can fail a 1% aqueous solution APHA colour limit below 150. Batch-to-batch variance in naphthalene content also shifts the required formaldehyde charge: excess formaldehyde above 1.0 mol/mol causes gel particles, while insufficient formaldehyde below 0.85 mol/mol reduces molecular weight and water-reducing efficiency.
When the cracked naphthalene fraction is routed to naphthol and azo intermediate plants, distillation or crystallisation is normally required to reduce 1-methylnaphthalene and 2-methylnaphthalene below 3–5 wt% combined because alkylated aromatics survive the first sulfonation step and later form alkylnaphthols during alkali fusion. In β-naphthol production, naphthalene is sulfonated at 155–165°C to favour the β-sulfonic acid isomer; the fusion mixture is charged to a molten caustic pot at 300–320°C and held for several hours to form sodium β-naphtholate. The melt is quenched in water, neutralized with sulfuric acid and steam-distilled to recover β-naphthol, which is then recrystallised or vacuum-distilled. The product is consumed as a coupling component in acid and dispersion dyes, as well as in 2-hydroxy-3-naphthoic acid for red and maroon pigments. Process control data from toll manufacturers indicate that a high acenaphthene content in the C10 feed raises the heavy end load in fusion pots and shortens the interval between alkali melt cleanouts. Export batches are commonly tested for β-naphthol purity by GC-FID, solidification point, and naphthylamine content due to REACH restrictions on amine impurities; a typical parametric sheet lists purity ≥99.0%, solidification point 121–123°C, and 1-naphthol ≤0.3 wt%.
Occasionally, cracking naphthalene fraction is injected into carbon black feedstock blending systems as a high-aromaticity modifier for density and Bureau of Mines Correlation Index control, not as a direct replacement for clarified oil or ethylene tar. Storage tanks and transfer lines are heated to 70–90°C because the cut can solidify below 60°C and plug rotameter loops. The blended feedstock is atomised into a refractory-lined furnace at 1400–1800°C, quenched with water after 0.05–0.5 s, and sent to bag filters; the resulting carbon black grade is determined by reactor cut, air-to-oil ratio and quench position. Feedstock sulfur content below 1.5 wt%, ash below 0.05 wt% and sodium plus potassium below 5 mg/kg are typical control points to protect furnace refractory and sustain product consistency. Carbon black surface area and structure are verified by ASTM D6556 and ASTM D2414 DBP absorption. High unsaturates in cracked naphthalene fraction can increase pyrolysis pitch deposition in quench sections and coolers; therefore, filter cleaning intervals are monitored when cracked C10 blend ratios exceed 10 wt% of total feedstock.
Recovered naphthalene from cracked C10–C12 material is also converted to short-chain alkyl naphthalene sulfonates used as wetting agents in agrochemical formulations, textile processing and leather chemicals. The route starts with Friedel-Crafts alkylation of naphthalene with butyl or propyl alcohol/olefin in the presence of an acid catalyst; the resulting alkyl naphthalene is sulfonated at 30–60°C and neutralized to produce aqueous solutions or dry sodium salts. Wetting power is evaluated by canvas disk immersion tests or internal drawdown tests at 1–5 g/L active content, while foam behaviour is checked by the Ross-Miles method. In textile scouring, the product is applied at 0.5–2.0 g/L in alkaline baths at 40–80°C. Traces of biphenyl and acenaphthene in the cracked naphthalene feed can alter surfactant colour and foaming; manufacturers of low-colour grades therefore impose feed purity limits of naphthalene ≥90 wt% and biphenyl ≤2 wt%. REACH registration dossiers for naphthalene derivatives require aquatic toxicity and biodegradation data under OECD 301 series methods; export documentation normally includes the safety data sheet classification for naphthalene as Carcinogenicity Category 2 under CLP, not as a formulation statement.
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Cracking Naphthalene Fraction is a complex aromatic hydrocarbon stream recovered from high-temperature cracking units, most commonly from ethylene plant pyrolysis gasoline and heavy pyrolysis tar distillation. The material is not a single-component naphthalene product; it contains naphthalene, methylnaphthalenes, biphenyl, acenaphthene, indene and minor thiophenic compounds. The boiling range typically spans 200 °C to 280 °C, with naphthalene content varying from approximately 40 wt% in middle cuts to above 95 wt% in concentrated grades. Product models are commonly supplier-specific codes structured as CNF-[minimum naphthalene content], such as CNF-80, CNF-90 and CNF-95, where the numeral indicates the minimum naphthalene content in percent by mass on a dry basis. The fraction is traded as an intermediate for naphthalene purification, phthalic anhydride production, naphthalene sulfonate manufacture and aromatic resin feedstock blending.
The critical difference is heteroatom profile and aromatic distribution. Coal tar naphthalene oil carries appreciable phenol, cresols and pyridine bases, which are largely absent from petroleum cracking fractions. Cracking-derived material instead contains thiophenic sulfur and higher alkyl naphthalenes. Sulfur content, measured by ASTM D4294, commonly falls between 0.1 wt% and 1.5 wt%. Nitrogen, measured by ASTM D5762, is typically below 0.2 wt%. Coal tar naphthalene oil often contains nitrogen between 0.5 wt% and 1.5 wt% and sulfur between 0.3 wt% and 1.0 wt%. The difference affects downstream catalyst tolerance: phthalic anhydride vanadia catalysts accept sulfur up to a defined threshold, while basic nitrogen compounds compete for active sites. Distillation curves also differ; the cracking fraction produces less phenolic tar residue during alkali washing.
Applications in phthalic anhydride production require close specification of unsaturated compounds and sulfur. Feedstock naphthalene content below 90 wt% increases the oxidation side-product load and can shorten catalyst life because methylnaphthalenes oxidize to naphthoquinones and phthalaldehydes. Published industrial guidance for fixed-bed oxidation indicates that total sulfur should be maintained below 0.5 wt% for vanadium–potassium catalysts, with nitrogen compounds limited to less than 0.1 wt% by ASTM D5762. Cracking naphthalene fractions with sulfur above this bound are pre-treated by hydrodesulfurization or caustic extraction before entering oxidation reactors. Batch-to-batch variation in catalytically cracked material requires downstream analytical screening because reactive olefins and indene can polymerize on preheater surfaces if the material is held above 200 °C for more than 24 hours.
Sulfonation with concentrated sulfuric acid or oleum proceeds in cast iron or steel reactors at 160–170 °C. The presence of acenaphthene and methylnaphthalenes above 15 wt% produces sulfonation sludge and increases free sulfuric acid in the final naphthalene sulfonate. A crystallisation point determined by ASTM D1493 of 78–79 °C indicates high naphthalene content but also requires heated storage above 85 °C. For CNF-95, the crystallisation point is typically 78.0–79.5 °C. When CNF-80 is used, solidification begins near 60–70 °C depending on methylnaphthalene content, allowing unheated handling in some climates but resulting in lower sulfonation yield. Processing windows are narrow: if the fraction drops below its crystallisation point in a storage tank, line clearing must use external tracing with hot oil at 100–110 °C.
Because the product is not refined to a single chemical standard, suppliers publish grade-specific assay ranges. The following table summarises typical specification ranges observed for petroleum-derived cracking naphthalene fractions; values are supplier-specific and not to be used as purchase limits without analytical verification.
| Property | Test method | CNF-80 | CNF-90 | CNF-95 |
|---|---|---|---|---|
| Naphthalene content | Supplier GC-FID | 80–85 wt% | 90–94 wt% | 95–98 wt% |
| Density at 90 °C | ASTM D4052 | 0.98–1.02 g/cm³ | 0.99–1.03 g/cm³ | 0.97–1.01 g/cm³ |
| Sulfur content | ASTM D4294 | 0.8–1.5 wt% | 0.3–0.8 wt% | 0.1–0.4 wt% |
| Nitrogen content | ASTM D5762 | <0.3 wt% | <0.2 wt% | <0.1 wt% |
| Solidification point | ASTM D1493 | 55–70 °C | 70–78 °C | 78–80 °C |
| Flash point | ASTM D92 | 95–120 °C | 100–125 °C | 95–115 °C |
| Distillation range 5–95 vol% | ASTM D86 | 210–280 °C | 215–280 °C | 218–260 °C |
Storage requires inert gas blanketing because unsaturated components react with oxygen. Tanks should be fabricated from carbon steel with internal heating coils; stainless steel type 316 is specified when sulfidation corrosion from sulfur species is expected. The material is incompatible with strong oxidizers, direct flame heating and prolonged air exposure above 80 °C. Water content must be kept below 0.1 wt% for sulfonation feedstocks because free water dilutes acid and reduces sulfonation rate. Pumping viscosity at 80 °C measured by ASTM D445 is typically below 20 mm²/s for CNF-80 and below 5 mm²/s for CNF-95, but viscosity rises sharply as the solidification point is approached.
In phthalic anhydride oxidation, cracking naphthalene fraction with naphthalene content above 90 wt% is associated with molar yields between 0.85 and 0.92 mole phthalic anhydride per mole naphthalene in fixed-bed reactors at 340–380 °C; actual values vary with catalyst age and air-to-feed ratio. In carbon black feedstock blending, the high aromatic carbon content of the fraction raises aromaticity relative to light cycle oil. A typical cracking naphthalene fraction shows aromatic carbon content above 80 wt% by ASTM D5186 or equivalent, supporting its use as an aromaticity enhancer in heavy fuel oil and carbon black feedstocks. However, its sulfur content can require flue gas desulfurization where SOx limits are enforced. In naphthalene sulfonate production, the sulfonation molar ratio of sulfuric acid to naphthalene is maintained at 1.3:1 to 1.4:1. The presence of methylnaphthalenes consumes acid and increases free acid in the condensate.
| Parameter | Cracking naphthalene fraction | Coal tar naphthalene oil | Light cycle oil |
|---|---|---|---|
| Naphthalene content | 40–95 wt% depending on cut | 70–85 wt% | 2–15 wt% |
| Density at 20 °C for liquid cuts | 1.02–1.08 g/cm³ | 1.03–1.10 g/cm³ | 0.93–0.98 g/cm³ |
| Sulfur by ASTM D4294 | 0.1–1.5 wt% | 0.3–1.0 wt% | 0.2–1.5 wt% |
| Nitrogen by ASTM D5762 | <0.3 wt% | 0.5–1.5 wt% | <0.2 wt% |
| Primary heteroatom impurities | thiophenes, mercaptans | phenols, pyridine bases | thiophenes |
| Major aromatic impurities | methylnaphthalenes, biphenyl, acenaphthene | indene, methylindene, phenol, cresol | alkylbenzenes, indane, naphthalene |
| Typical use | naphthalene recovery, phthalic anhydride | naphthalene purification | FCC feed or fuel blendstock |
Fractional distillation and static crystallization are the primary purification routes. Static crystallization at 78–80 °C followed by sweating produces naphthalene with purity above 99 wt% suitable for phthalic anhydride. Cracking naphthalene fractions containing acenaphthene above 5 wt% require additional distillation at 270–280 °C because acenaphthene has a boiling point higher than naphthalene; single-stage crystallization alone can leave residual contamination due to solid-solution formation. Published data for this specific separation configuration is limited; design of crystallization trains relies on pilot-scale solid–liquid equilibrium measurement. In transfer, the fraction is preheated to 85–90 °C to maintain homogeneous liquid composition and avoid settling of high-melting components.
