Main-Product

Refinery waxes are hydrocarbon products derived from petroleum refining, synthetic gas-to-liquids processes, polyolefin manufacturing, and chemical recycling of plastic waste. These waxes consist primarily of long-chain alkanes and serve diverse industrial applications ranging from candles and packaging to adhesives and polymer processing.

Traditional Petroleum-Derived Waxes

Slack Wax

Slack wax is a crude, semi-refined by-product recovered from the solvent dewaxing unit during lubricating oil production in petroleum refineries, where it separates from base oil stocks as the waxy fraction. It consists of a heterogeneous mixture containing 30-60% residual oil blended with straight-chain (normal) paraffin hydrocarbons, plus varying amounts of branched isoparaffins and naphthenic compounds. Slack wax serves as the primary feedstock for producing refined paraffin waxes through subsequent processing steps including de-oiling (sweating or solvent extraction) and bleaching. Light slack wax grades (melting point 50-52°C, lower oil content) are typically processed into fully-refined paraffin wax for high-purity applications in cosmetics and food-grade products, while heavy slack wax grades (melting point 53-55°C with 5-35% oil content) are converted to semi-refined paraffin wax for industrial uses including candles, rubber compounds, adhesives, and inks.

Paraffin Wax

Paraffin wax is produced by de-oiling slack wax through solvent extraction or crystallization processes in the refinery wax plant. It consists predominantly of straight-chain (normal) alkanes typically ranging from C₂₀ to C₄₀, with minimal branching, resulting in a highly crystalline structure characterized by large visible crystals and brittle texture. Paraffin wax exhibits melting points ranging from 49-71°C (120-160°F), low residual oil content (typically <0.5% for fully-refined grades), and a translucent white appearance. Its high crystallinity and clean-burning properties make it ideal for applications requiring rigidity, such as candles, coatings, and food-grade uses.

Petrolatum (Petroleum Jelly)

Petrolatum, commonly known as petroleum jelly or by the brand name Vaseline, is a semi-solid colloidal system produced during the vacuum distillation and dewaxing of heavy lubricating oil fractions in petroleum refineries. It consists of a complex mixture containing microcrystalline wax components (providing structure) dispersed in liquid mineral oil (25-40%), with the hydrocarbon composition dominated by branched isoparaffins and cyclic naphthenic structures in the C₂₅-C₅₀ range, plus smaller amounts of aromatic compounds. This high proportion of branched and cyclic hydrocarbons prevents crystallization into a solid wax structure, instead forming a unique gel-like, semi-solid consistency with excellent moisture-retention and occlusive properties. Petrolatum typically exhibits melting points of 55-63°C (130-145°F) and remains semi-solid at room temperature. Fully-refined pharmaceutical and cosmetic grades (white petrolatum) undergo extensive purification to remove aromatics and achieve colorless, odorless properties for use as skin protectants and ointment bases, while technical-grade petrolatum can be further processed through de-oiling to produce microcrystalline wax for industrial applications.

Microcrystalline Wax

Microcrystalline wax is produced in refinery wax plants by de-oiling petrolatum or heavy residual oil fractions using selective solvent extraction processes. Unlike paraffin wax, it contains a higher percentage of branched isoparaffinic hydrocarbons (25-50%) and cyclic naphthenic compounds, typically in the C30-C60 range, which disrupt crystal formation. This composition results in very fine, tight microcrystals (smaller than 1 micron) that provide a flexible, tacky consistency with superior oil-holding capacity and adhesive properties. Microcrystalline wax exhibits melting points of 60-88°C (140-190°F), higher viscosity than paraffin wax, and a soft, pliable texture rather than brittleness, making it suitable for adhesives, cosmetics, rubber compounds, and protective coatings.

Fischer-Tropsch (FT) Synthetic Waxes

Fischer-Tropsch wax is a synthetic wax produced via gas-to-liquids (GTL) technology through the polymerization of carbon monoxide and hydrogen (synthesis gas) under high pressure using cobalt-based catalysts. These waxes feature a highly linear structure with high crystallinity and melting points ranging from 45-116°C. FT waxes are produced from natural gas feedstock through the GTL process, with hydrocarbon products distilled to separate fuels and waxes. They are characterized by low oil content (typically ≤0.5-1.0%), high purity with less than 50 ppm cobalt particulates, and superior performance properties.

Polyolefin Waxes

Purposely-Produced Polyolefin Waxes

Polyolefin waxes are low-molecular-weight polyethylene or polypropylene products (molecular weight 1,000-4,000) produced through three primary routes:

1. Direct polymerization/oligomerization of ethylene monomers - using free radical polymerization, Ziegler-Natta catalysts, or metallocene catalysts under controlled conditions to produce low-molecular-weight polyethylene
2. Thermal degradation of high-molecular-weight polyethylene - breaking down polymer chains to lower molecular weight fractions​
3. Separation methods - extracting lower molecular weight fractions from standard polyethylene production​

These waxes exhibit white to light yellow appearance, low toxicity, high softening points, low melt viscosity, and excellent lubricity and dispersion properties.​

Co-Products from Polymerization

Polyethylene wax can be recovered as a by-product from high-pressure polyethylene synthesis processes. After removing solvents and initiators from the low-molecular-weight components obtained during ethylene polymerization, these by-product waxes contain molecules with relative molecular weights around 1,000. However, their wide molecular weight distribution limits application fields and typically requires further purification by solvent separation, resulting in lower mechanical strength and heat resistance compared to purposely-produced polyethylene waxes.​

Chemical Recycling Waxes

Pyrolysis-Derived Waxes

Waxes can be produced through thermochemical pyrolysis of plastic waste, including polyethylene (HDPE, LDPE), polypropylene, and polystyrene feedstocks. Pyrolysis of waste agricultural film and plastic solid waste at temperatures of 380-410°C for 15-45 minutes yields waxes with molecular weights of 2,000-7,000 g/mol, melting points of 107-123°C, and yields exceeding 95%. The highest wax yield (64.5 wt%) is obtained from LDPE at 500°C.

Pyrolytic waxes from plastic waste demonstrate densities of 849-880 kg/m³, similar to commercial wax products, and calorific values of 45.61-46.22 kJ/g, comparable to kerosene and gas oil. The production mechanism involves creation, transfer, isomerization, recombination, and dehydrogenation of free radicals during PE pyrolysis.

Purification and Upgrading

Waxes produced from depolymerized plastic waste can be upgraded by blending with Fischer-Tropsch wax, which acts as an effective solvent due to its linear structure and high crystallinity. This blend is subjected to filtration using diatomaceous earth or activated carbon to remove contaminants, improving viscosity and enabling functionalization without requiring subsequent distillation to separate the FT wax component. However, pyrolytic waxes often require color improvement, as waste film-derived waxes exhibit low initial whiteness (19.8) due to inorganic salts, conjugated compounds, and aromatic structures; selective hydrogenation can enhance whiteness to 85.4.