Tire Pyrolysis Oil Purification: Decolorization, Desulfurization & Upgrading with Silica Gel Sand

Introduction: The Gap Between Pyrolysis Oil and Refinery Feedstock

Tire pyrolysis is one of the most commercially viable routes for waste tire recycling. A well-run pyrolysis plant can achieve liquid oil yields of 50–52%, with light fractions (gasoline and diesel range) accounting for over 70% of the oil produced. The global tire pyrolysis oil market continues to expand as regulations tighten on waste tire disposal and demand grows for circular economy solutions.

But raw tire pyrolysis oil is not a finished product. It is a dark, odorous liquid loaded with sulfur compounds, nitrogen-containing species, oxygenates, and carbonaceous color bodies. Direct use as fuel is limited by emissions regulations. Direct blending into refinery feedstock is limited by catalyst poisoning risk. The gap between raw pyrolysis oil and a marketable product is closed by purification and upgrading — and the choice of purification method determines the quality, yield, and economics of the final product.

This article focuses specifically on one stage of that purification chain: decolorization and polar impurity removal using silica gel sand, and how it fits into the broader tire pyrolysis oil upgrading process.

Tire pyrolysis oil is fundamentally different from crude oil or waste lubricants. Its contamination profile is shaped by the feedstock:

1. High sulfur content. Tires contain 1–2% sulfur by weight from vulcanization. During pyrolysis, this sulfur converts into hydrogen sulfide, mercaptans, thiophenes, and benzothiophenes — all of which persist in the oil. The sulfur content of raw tire pyrolysis oil typically ranges from 0.8% to 1.5%, far above the limits for transportation fuels.

2. Nitrogen and oxygen compounds. Tire formulations include accelerators, antioxidants, and other additives containing nitrogen and oxygen. These convert into pyridines, quinolines, phenols, and carboxylic acids during pyrolysis, contributing to gum formation, color instability, and corrosion.

3. Carbonaceous color bodies. The characteristic black color of tire pyrolysis oil comes from fine carbon black particles, heavy resinous compounds, and asphaltene-like materials. These are not merely cosmetic — they interfere with downstream catalysts and reduce product value.

4. High total acid number (TAN). Oxygenated compounds and carboxylic acids give tire pyrolysis oil an elevated TAN, which promotes corrosion in storage and handling equipment.

5. Instability. Raw tire pyrolysis oil is chemically unstable. Dissolved olefins and oxygenates polymerize over time, causing color reversion, sediment formation, and viscosity increase during storage.

Tire pyrolysis oil upgrading typically follows a multi-stage sequence. No single technology solves every problem, and the order of operations matters.

Raw oil is heated to remove water and settled or filtered to remove large carbon black particles. This is a mechanical pretreatment step.

The oil is distilled into boiling-range cuts — typically a light naphtha/gasoline fraction, a diesel-range fraction, and a heavy residue. Distillation concentrates sulfur and nitrogen compounds into specific fractions and removes the heaviest resinous material. It is the single most important step for improving oil quality.

After distillation, the lighter fractions — particularly the diesel-range cut — still carry dissolved color bodies, polar compounds, and residual sulfur species. This is where silica gel sand delivers its value.

Silica gel sand is a white, granular adsorbent with a specific surface area of 300–500 m²/g and a pore diameter of 85–110 Å. Its highly porous structure selectively adsorbs:

The oil passes through a bed of silica gel sand, and these impurities are captured in the pore structure. The result is a lighter-colored, more stable oil that meets downstream specifications.

For refinery-grade feedstock, the polished oil may require hydrotreating to saturate olefins and remove residual sulfur and nitrogen. Silica gel sand polishing upstream of hydrotreating reduces catalyst poisoning risk by removing the polar compounds that deactivate catalysts.

Tire pyrolysis oil decolorization requires an adsorbent that can capture carbonaceous and resinous color bodies without clogging or channeling. Silica gel sand's granular form and high surface area make it effective for this application, achieving a decolorization rate of ≥98% on standard grades.

Unlike clay-based bleaching earth, which requires thermal activation and can generate acidic sites that catalyze unwanted side reactions, silica gel sand works through physical adsorption at ambient or slightly elevated temperatures. This preserves oil quality and avoids the color reversion that can occur with thermally treated clays.

The waste residue from silica gel sand does not stick, agglomerate, or solidify. This makes spent sand easier to handle, transport, and dispose of — or in some cases, utilize as fuel — compared to clay residues that form hard cakes and require special disposal.

Silica gel sand can be used to polish individual distillation cuts or the combined oil. Its pore size is well-suited to the molecular size range of the color bodies and polar impurities found in the diesel-range fraction.

One ton of silica gel sand can treat approximately 50–200 tons of oil, depending on the oil quality and processing conditions. For pyrolysis oil operators, this translates into a low per-ton adsorbent cost.

Silica gel sand is used in filter tanks or adsorbent contact columns. The oil is pumped through the sand bed, and the impurities are adsorbed. The equipment requirements are straightforward:

with appropriate diameter and bed depth

to drive oil through the bed

if the oil contains volatile hydrocarbons

to track bed saturation

For larger operations, twin-tank systems allow continuous operation — one tank in service while the other is being reloaded. For smaller operations, single-tank systems with batch operation are sufficient.

The same equipment used for diesel decolorization and waste lubricant polishing can be used for tire pyrolysis oil fractions, making it a versatile investment for multi-product oil recycling operations.

It is important to be clear about the limits of silica gel sand treatment:

Silica gel sand removes polar sulfur species, but thiophenic sulfur — the most refractory sulfur compounds — requires hydrotreating or specialized desulfurization adsorbents.

It removes color bodies and polar impurities; it does not change the hydrocarbon backbone of the oil.

Distillation is the primary separation step; silica gel sand is a polishing step downstream of distillation.

If the distillation is poorly controlled and the cut point is too high, silica gel sand cannot compensate for the heavies that should not be in the fraction.

Understanding these limits is what separates a professional adsorbent supplier from one who simply sells sand.

Tire pyrolysis oil upgrading is a margin-driven business. The difference between selling raw black pyrolysis oil and selling a light-colored, specification-grade product can be substantial. Silica gel sand polishing adds cost — but it also adds value:

Decolorized oil commands a premium over raw black oil

Cleaner oil can be sold to more customers, including those with color specifications

Removing polar compounds before hydrotreating extends catalyst life

Clean spent sand is easier to handle than clay residue

For operators producing tire pyrolysis oil at scale, silica gel sand polishing is not an expense — it is an investment in product quality and market access.

Particle size (2–5 mm, 4–8 mm, 20–200 mesh) and packaging can be tailored to your filter tank configuration and process requirements. Please provide your oil characteristics and treatment objectives for a tailored recommendation.

Decoloring rate ≥98%, SiO₂ content ≥98%

We understand the specific challenges of tire and plastic pyrolysis oil purification

Filter tanks available for silica gel sand application

Our team can help select the right grade and bed configuration for your oil stream

Stable supply and factory-direct pricing

Efficient shipping from major Chinese ports

It is the process of removing impurities — sulfur compounds, nitrogen compounds, color bodies, and polar species — from raw tire pyrolysis oil to produce a cleaner, more marketable product. It typically involves distillation followed by adsorbent polishing.

Silica gel sand removes polar sulfur species, but thiophenic sulfur — the most refractory sulfur compounds — requires hydrotreating or specialized desulfurization. Silica gel sand is a polishing step, not a standalone desulfurization solution.

The decolorization rate is ≥98%. The final color depends on the starting oil quality, the distillation cut point, and the amount of adsorbent used. With proper distillation and polishing, a light yellow to near-water-white oil can be achieved.

One ton of silica gel sand can treat approximately 50–200 tons of oil, depending on the oil quality and processing conditions. The optimal dosage should be determined through testing on your specific oil.

Yes. The same filter tanks used for diesel decolorization can be used for pyrolysis oil fractions. The bed depth and flow rate may need adjustment, but the equipment is compatible.

Spent silica gel sand does not agglomerate or solidify. It can be disposed of as solid waste or utilized as fuel in some applications. This is easier to handle than spent clay residue.

Yes. Samples can be provided for evaluation on your specific pyrolysis oil. Please contact us with your oil characteristics and treatment objectives.

For quotations, technical data sheets, or samples of silica gel sand for tire pyrolysis oil purification:

📧 Email: info@jusenchem.com

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