Molecular Sieve Poisoning by H2S: Detection, Recovery, and Prevention in Sour Gas Service

Why H2S Poisoning Is the #1 Cause of Unplanned Molecular Sieve Replacement

Across the molecular sieve industry, hydrogen sulfide accounts for an estimated 35 to 45% of all unplanned bed replacements in natural gas and biogas service, and a similar share in refinery dry gas and EOR CO2 dehydration. The reason is straightforward: H2S reacts with the extra-framework cations inside every common zeolite (4A, 5A, 13X) to form stable sulfide salts that physically block the pore openings and chemically deactivate the adsorption sites. Once this happens, the damage is partly irreversible. Sieve life drops from a designed 3 to 5 years to 6 to 12 months, and operators face a recurring replacement cost that often runs 50,000 to 200,000 USD per year for a mid-sized plant.

This guide is written for the engineer, plant operator, or procurement specialist who has to deal with sour gas feed and molecular sieve in the same sentence. We will cover:

• The chemistry of H2S-zeolite reaction and why 13X is worse than 4A and 5A
• Real field breakthrough curves and damage thresholds in ppmv and wt%
• The 7-step detection protocol used in refinery and biogas labs
• What is recoverable with regeneration and what must be replaced
• Guard bed design: ZnO, iron sponge, activated carbon, and biological desulfurization
• COS and mercaptan damage - the often-overlooked secondary poisoning
• H2S-resistant sieve grades: dealuminated Y, iron-exchanged 5A, zinc-based adsorbents
• Cost economics: guard bed CAPEX vs unplanned replacement OPEX

By the end you should be able to look at a feed gas spec, predict sieve life within a factor of two, and decide whether a guard bed is justified for your specific application.

The Chemistry: How H2S Attacks a Zeolite

To understand H2S poisoning you need to know what is inside a dehydrated zeolite crystal. Every commercial molecular sieve is an aluminosilicate framework (SiO2 and AlO4 tetrahedra linked by shared oxygen atoms) with charge-balancing cations sitting in well-defined extra-framework sites. The cations are what make the sieve adsorb water, CO2, and other polar molecules - they create the local electric field that polarizes the adsorbate and pulls it into the pore.

For the three most common sieves:

• 4A: A-type framework, pore opening ~4 Angstrom, ~12 Na+ per unit cell (dehydrated form)
• 5A: A-type framework, pore opening ~5 Angstrom, ~12 Ca2+ per unit cell (after calcium exchange)
• 13X: X-type faujasite framework, pore opening ~10 Angstrom, ~86 Na+ per unit cell

When H2S enters a hot or even warm bed it dissociates on the cation sites: H2S adsorbs as a molecule first, then deprotonates to form HS- and S2- on the basic oxide cation. The reactions look like this:

2 Na+ + H2S  →  Na2S + 2 H+ (on the framework oxygen)
Na+ + H2S  →  NaHS + H+ (proton goes to a framework oxygen)
Ca2+ + H2S  →  CaS + 2 H+ (less thermodynamically favorable)

Na2S, NaHS, and CaS are ionic salts with melting points above 800 degrees C. Once formed inside the zeolite pore they are essentially impossible to remove by ordinary temperature swing regeneration (200 to 250 degrees C) - the salt is stuck. Worse, the volume of the salt physically blocks the pore, and the loss of the original cation means that even sites that are not yet sulfided lose their ability to polarize water and CO2.

This is the fundamental reason H2S damage is so hard to reverse: you are not just adsorbing a poison, you are precipitating a salt.

Why 13X is the worst

13X has roughly 7 times more sodium cations per unit cell than 4A or 5A. That means 7 times more potential sulfide nucleation sites per gram of sieve. The X-type faujasite framework also has a wider pore opening (10 Angstrom) and larger supercage, which lets H2S diffuse in quickly. The combination of high cation density and open pore structure makes 13X the most H2S-sensitive of the standard sieves. In a side-by-side test feeding 20 ppmv H2S in dry methane at 35 degrees C and 7 bar, 13X loses 50% of its water capacity in 28 days, while 5A loses 50% in 92 days under identical conditions.

Why specialty Ag-X and Cu-X are even worse

Some adsorbents, particularly silver-exchanged X (Ag-X) used for olefin/paraffin separation, are extremely H2S-sensitive because Ag2S has a solubility product (Ksp) of about 6 x 10^-50 - essentially zero. Once silver sulfide forms inside the framework, the only practical recovery method is acid washing, which destroys the silver exchange. Copper-exchanged Y is similarly affected. These specialty sieves must never be exposed to feed H2S above 0.1 ppmv without a guard bed.

Damage Thresholds: How Much H2S Is Too Much

There are three different ways engineers express H2S damage thresholds, and they are often confused. Let us sort them out:

1. Feed gas concentration (ppmv or mg/Nm3): the easiest to measure - the H2S content of the inlet gas. Most relevant for guard bed design.
2. Cumulative exposure (kg H2S per ton of sieve): the total mass of H2S that has passed through the bed over its lifetime. Most relevant for sieve life prediction.
3. Sieve sulfur content (wt% S): the actual sulfide loading in the zeolite, measured by digestion and ICP. The most reliable indicator of actual damage.

The table below summarizes industry-typical damage thresholds. The numbers are derived from our in-house testing plus published field data from UOP, CECA, Zeochem, and operating records from refinery and biogas plants we supply.

The "S content at failure" column is the most important one to understand. It is the actual amount of sulfur in the sieve when capacity has dropped to 80% of fresh-sieve value, which is the typical end-of-life criterion. The 0.5 to 1.0 wt% range corresponds to roughly 5 to 10 kg of bound sulfur per metric ton of sieve. Once you reach that loading, regeneration cannot fully restore the bed.

Real Breakthrough Curves from Sour Gas Service

The breakthrough curve is the plot of outlet H2S concentration versus time, and it tells you exactly when your guard bed must be replaced or regenerated. Here is a representative curve from a real biogas upgrading plant:

Notice the S-shape of the breakthrough curve. In the first 3 to 6 months the bed is doing its job - outlet H2S stays below the detection limit. Between month 6 and month 9 the lead edge of the bed becomes saturated with sulfide and outlet H2S starts to climb. By month 9 the outlet is within 1 ppmv of the inlet, and the bed is no longer providing any protection. At that point the 13X has lost 30 to 40% of its original water and CO2 capacity, and continued operation damages the downstream adsorber as well.

This curve is for a relatively modest 8 ppmv H2S feed. In a refinery dry gas or EOR CO2 stream at 100 to 500 ppmv H2S, the same S-curve plays out in 4 to 8 weeks instead of 12 months.

The 7-Step Field Detection Protocol

Refinery and biogas plant labs have converged on a similar protocol for detecting H2S poisoning before it forces an unplanned shutdown. Here is the 7-step sequence we recommend, with the equipment and decision criteria for each step:

1. Step 1 - Continuous outlet H2S monitoring: Install a Drager Polytron or equivalent electrochemical H2S sensor on the outlet of each molecular sieve bed. Set alarm at 0.1 ppmv for medical/biogas service, 4 ppmv for pipeline natural gas, 10 ppmv for industrial process gas. The sensor must be downstream of the bed but upstream of any product gas cooler where H2S might re-equilibrate.
2. Step 2 - Outlet dew point tracking: In dehydration service, the outlet dew point is your best early warning. A rise of 5 degrees C from baseline indicates ~10% capacity loss. A rise of 10 degrees C means ~25% loss. Compare to inlet dew point - the ratio tells you how much of the bed is still active.
3. Step 3 - Pressure drop profile: A poisoned bed develops non-uniform pressure drop because the leading edge becomes denser (sulfided) and the trailing edge remains loose. Measure delta P across the bed in 25% increments (4-point measurement). A "step" profile - high delta P in the first 25% and low in the rest - is diagnostic of leading-edge sulfiding.
4. Step 4 - Visual bed inspection at turnaround: During scheduled maintenance, extract 200 to 500 g samples from the top, middle, and bottom of the bed. H2S-poisoned sieve is often visibly darker - white to off-white fresh sieve turns to tan, gray, or black. Color alone is not diagnostic, but combined with step 5 it is conclusive.
5. Step 5 - ICP-OES or ICP-MS sulfur analysis: Send the samples to a lab for acid digestion followed by inductively coupled plasma analysis. Report sulfur in wt%. Values below 0.1 wt% S = healthy, 0.1 to 0.3 wt% S = early damage, 0.3 to 0.5 wt% S = significant damage requiring planning for replacement, above 0.5 wt% S = end of life.
6. Step 6 - Water capacity check on extracted sample: Run a simple lab test: dry the sample at 250 degrees C for 2 hours, expose to 80% relative humidity at 25 degrees C for 24 hours, weigh the water uptake. Compare to fresh sieve of the same grade. A drop to 80% of fresh value is the industry threshold for end of life.
7. Step 7 - Bed replacement decision matrix: Combine steps 1 to 6. If two or more of: outlet H2S above limit, dew point rise above 10 degrees C, ICP sulfur above 0.3 wt%, water capacity below 85% fresh, are triggered, plan bed replacement within the next 3 to 6 months. If three or more are triggered, schedule replacement at the next available turnaround.

Steps 1 to 3 are online and continuous. Steps 4 to 6 are offline and run at scheduled maintenance intervals (typically annually). Step 7 is the management decision layer that turns raw data into action.

What Is Recoverable and What Is Not

The question every operator asks is: can I regenerate the poisoned sieve and get back to full capacity? The honest answer is "partly, but not fully." Here is the breakdown:

The hot TSA at 300 to 350 degrees C is the workhorse of partial recovery. It removes the physically adsorbed H2S and decomposes some of the NaHS back to Na+ and H2S, but it cannot touch the more stable Na2S. The acid + re-exchange option can recover 85 to 95% of original capacity and is occasionally used in the catalyst regeneration industry, but it is not cost-effective for commodity molecular sieve. A typical 10-ton bed with mid-life poisoning would cost 30,000 to 60,000 USD to ship, regenerate, and return - comparable to fresh sieve cost.

The practical conclusion: if a bed has reached 30 to 50% capacity loss, replace it. Treat the regeneration as a one-time emergency measure to keep the plant running for a few months while fresh material is procured.

Guard Bed Design: ZnO, Iron Sponge, Activated Carbon, Biological

The cheapest way to deal with H2S poisoning is to prevent H2S from ever reaching the molecular sieve. Guard beds are designed for exactly this purpose, and the right choice depends on the H2S concentration, the temperature, the presence of other contaminants, and the budget.

For most natural gas dehydration and EOR CO2 applications, zinc oxide is the gold standard. The reaction ZnO + H2S to ZnS + H2O is thermodynamically favorable down to outlet H2S below 0.05 ppmv at 200 to 400 degrees C, which is below the threshold for any practical molecular sieve. ZnO beds are sized for 6 to 24 months of service between replacements and the spent ZnS is a non-hazardous solid that can be sent to a zinc smelter for recovery.

For biogas upgrading, the modern approach is a two-stage system: biological desulfurization on a Thiobacillus-packed biofilter drops H2S from 500 to 3000 ppmv down to 5 to 20 ppmv, and an activated carbon polishing bed with KI/KOH impregnation takes the outlet to below 0.1 ppmv. This is the lowest OPEX option for high-H2S feed gas and is now standard in plants above 500 Nm3/h.

COS and Mercaptans: The Hidden Secondary Poisoning

In refinery and natural gas service, H2S is rarely the only sulfur compound. COS (carbonyl sulfide) and mercaptans (R-SH, where R is methyl, ethyl, propyl, etc.) are often present at comparable or higher concentrations, and they can be more damaging to molecular sieve than H2S itself.

COS (carbonyl sulfide)

COS hydrolyzes on the acid sites of zeolites via the reaction COS + H2O to H2S + CO2. This means COS that enters the molecular sieve bed is converted in situ to H2S, which then does the actual poisoning. The hydrolysis reaction is fast at 100 to 200 degrees C and slower at room temperature, but it does proceed at ambient on a wet zeolite. The implication is that a "COS-free" feed gas that has not been hydrolyzed can still damage the sieve if moisture is present.

COS removal options: a separate COS hydrolysis reactor on a promoted alumina catalyst (Clariant Cosmo, Johnson Matthey K-3-126, or equivalent) at 150 to 200 degrees C will convert 95 to 99% of COS to H2S, which is then removed by the downstream ZnO guard bed. This is the standard approach in LNG plants and ammonia syngas loops.

Mercaptans (R-SH)

Methyl mercaptan (CH3SH), ethyl mercaptan (C2H5SH), and propyl mercaptan are strong-smelling sulfur compounds that are adsorbed strongly and irreversibly by zeolites. Unlike H2S, mercaptans do not always form simple salts. Instead, they polymerize inside the pore channel to form high-molecular-weight polysulfide polymers. The polymers are solid, waxy, and essentially impossible to remove with thermal regeneration. A mercaptan-poisoned sieve looks and behaves like a bed contaminated with heavy oil - reduced capacity, slow kinetics, often accompanied by pressure drop problems.

Mercaptan removal: standard H2S guard beds (ZnO, iron sponge) have limited capacity for mercaptans. Activated carbon impregnated with Cu or Ag is more effective. Molecular sieves themselves are sometimes used as a mercaptan trap before another sieve bed, but this is a sacrificial use and the bed must be replaced frequently. In practice, mercaptan control is best done at the upstream amine contactor or with a dedicated molecular sieve 5A mercaptan removal bed operated at 200 to 250 degrees C with a 24-hour regeneration cycle.

H2S-Resistant Sieve Grades from Aluminaworld

For applications where guard beds are impractical or where feed H2S is too variable to be fully absorbed by the guard, specialty sieve grades extend bed life by a factor of 2 to 4. We supply three such grades from our Zibo facility:

DD-13X-S is the workhorse for natural gas dehydration where inlet H2S is 1 to 10 ppmv. The dealumination reduces cation density by 60 to 70%, which slows sulfide formation enough to extend bed life from 18 to 36 months (standard 13X) to 36 to 60 months. The trade-off is slightly lower equilibrium water capacity - 22 to 25 wt% vs 28 to 30 wt% for standard 13X. In most designs you simply increase bed mass by 10 to 15% to compensate.

DD-5A-Fe is for paraffin/normal alkane separation and bulk CO2 removal in EOR service where inlet H2S can spike to 20 to 50 ppmv. The iron exchange makes the sulfide formation partly reversible at 350 degrees C regeneration, which is the normal TSA cycle for 5A paraffin service. We have plants running on DD-5A-Fe for 24+ months in a 30 ppmv H2S feed that previously lasted only 6 months on standard 5A.

ZS-Series is a guard bed product, not a primary adsorbent. The 20 to 30 wt% H2S capacity means a single pass through 100 to 200 kg of ZS-Series drops 1000 ppmv feed to below 0.1 ppmv for 6 to 18 months, depending on the gas flow rate. Spent ZS-Series is non-hazardous and can be returned to a zinc refinery.

5 Real-World Case Studies

To make the guidance concrete, here are five real installations we have worked on. Names are omitted for confidentiality but the data is representative.

Case 1 - German biogas upgrading, 1500 Nm3/h

A 1500 Nm3/h biogas upgrading plant in Bavaria was experiencing 13X bed life of only 7 months. The plant was feeding raw biogas from a mixed agricultural digester with H2S varying from 50 to 300 ppmv depending on feedstocks. After a 6-step inspection revealed 0.7 wt% S in the spent sieve, the operator installed a two-stage guard system: Thiobacillus biofilter taking H2S from 200 ppmv to 5 ppmv, followed by a KI-impregnated activated carbon polisher to below 0.1 ppmv. New 13X bed installed at the same time. Expected service life with the new system: 5+ years. Annual savings on sieve replacement: approximately 95,000 EUR.

Case 2 - Chinese refinery dry gas dehydration

A 60,000 Nm3/h refinery dry gas dehydration unit in Shandong was originally designed with a 4A sieve in the lead bed and a 13X polishing bed. Feed H2S was 8 to 15 ppmv (typical of fluid catalytic cracker off-gas). The 4A lead bed had to be replaced every 10 months, and the 13X polishing bed was failing at 14 months. Inspection showed the 4A contained 0.5 wt% S and the 13X contained 0.3 wt% S. Solution: installed a 4-ton zinc oxide guard bed operating at 280 degrees C, which drops H2S to below 0.05 ppmv. New 4A and 13X beds installed. The guard bed is replaced annually at a cost of 18,000 USD, and the 4A and 13X beds have been in service for 4 years with no measurable capacity loss. Annual net savings: approximately 60,000 USD.

Case 3 - US EOR CO2 dehydration, 8000 Nm3/h

An enhanced oil recovery plant in West Texas captures CO2 from a natural gas processing stream and re-injects it for oil recovery. The CO2 feed contains 25 to 35 ppmv H2S and 5 to 8 ppmv COS after the amine contactor. Original 13X sieve bed was failing at 8 months with outlet dew point rising from -60 degrees C to -35 degrees C. We supplied a DD-13X-S replacement bed along with a 3-ton zinc oxide guard bed. New bed has been in service for 28 months with no measurable degradation, and outlet H2S is consistently below 0.05 ppmv.

Case 4 - Italian natural gas dehydration, 5000 Nm3/h

A natural gas dehydration unit in the Po Valley was running on 4A sieve with feed H2S of 2 to 4 ppmv. The plant was designed for 5A but switched to 4A for cost reasons. 4A lasted only 14 months in this service, against a 5A design life of 36 months. Operator replaced with our 5A (full calcium exchange) and added a small iron oxide guard bed. New 5A bed has been in service for 32 months and is still healthy. The lesson: cheaper sieve grade is not always cheaper overall when feed has contaminants that grade is sensitive to.

Case 5 - Indian EOR pilot, 200 Nm3/h

A small EOR pilot in Gujarat was using 13X to dehydrate CO2 from a biogas upgrading process. Feed H2S was 80 to 120 ppmv (no upstream amine treatment). Standard 13X failed in 4 months. Solution: ZS-Series guard bed in front of a standard 13X. The ZS-Series handles 90% of the H2S load and the 13X handles only the residual. The 13X has been in service for 22 months with no measurable damage. The ZS-Series is replaced every 14 months. This is a textbook guard bed + main bed configuration that is now standard for small EOR pilots in India.

How to Choose: A 5-Step Decision Tree

For a new installation or a major sieve replacement, work through this decision tree:

1. Step 1: Measure your feed H2S accurately. Use a calibrated electrochemical sensor or Draeger tube at the actual operating pressure and temperature. Lab analysis of a gas sample using ASTM D5504 or ISO 19739 is more accurate than field sensors. Confirm the reading over at least 7 days of operation - H2S in natural gas and biogas varies with feedstock and operating conditions.
2. Step 2: Identify all sulfur species. Request GC-SCD or GC-FPD analysis for H2S, COS, CS2, methyl/ethyl mercaptans, dimethyl sulfide, and tetrahydrothiophene. COS and mercaptans often account for 30 to 50% of total sulfur and are not detected by standard H2S-specific sensors.
3. Step 3: Estimate annual sulfur load. Multiply the total sulfur concentration (in ppmv or mg/Nm3) by the annual gas flow. This gives you the total kg of sulfur that the guard bed (and main bed, if no guard) must handle per year.
4. Step 4: Compare guard bed cost vs main bed replacement cost. If the annual sulfur load is above 100 kg/year and the main bed replacement cost is above 30,000 USD, a guard bed pays back in less than 2 years. For 500 kg/year sulfur load and main bed replacement above 50,000 USD, the guard bed pays back in 6 to 12 months.
5. Step 5: Select guard bed type based on H2S concentration and temperature. Use the guard bed selection table from section 6. For most natural gas and refinery service, zinc oxide is the default. For biogas with high H2S, use biological + activated carbon. For ambient-temperature CO2 service, ZS-Series zinc alumina is the cleanest solution.

If guard bed installation is not feasible (offshore platform, mobile unit, very small plant), the alternative is to use a specialty H2S-resistant sieve grade (DD-13X-S, DD-5A-Fe) and accept the higher unit cost as the price of operating without a guard. This is the right call for plants under 100 Nm3/h or where capital budget is constrained.

Cost Economics: Guard Bed vs Replacement OPEX

To put numbers on the decision, here is a 5-year TCO comparison for a typical 500 Nm3/h natural gas dehydration plant with 4A sieve and 8 ppmv H2S feed:

The numbers are clear. Even the most expensive option (DD-13X-S without guard bed) costs less over 5 years than running standard 13X with no protection, because it avoids the unplanned shutdown cost - which is often the largest component of total H2S-related expense. The ZnO guard bed approach has a slightly higher 5-year cost than DD-13X-S in this specific example, but it also protects the downstream adsorbers and product gas quality in a way that the sieve-only approach cannot. In practice, plant operators usually choose the guard bed for higher H2S feeds (above 10 ppmv) and the DD-grade sieve for lower H2S feeds (1 to 10 ppmv).

7 Common Mistakes When Operating Sieves in Sour Gas Service

1. Skipping the H2S measurement because the spec says "low H2S". Pipeline spec is not the same as operating reality. Always measure at the bed inlet, under actual operating conditions, for at least 7 days before committing to a sieve specification.
2. Assuming ZnO or iron sponge is "permanent". All guard beds have finite capacity. Plan for replacement based on cumulative sulfur loading, not calendar time alone.
3. Regenerating at temperatures that decompose the framework. Pushing TSA above 350 degrees C for extended periods on 4A or 13X causes dealumination. You can recover sulfide at the cost of framework damage. Not a net win.
4. Mixing H2S-poisoned sieve with fresh sieve in the same bed. If you top up a partially poisoned bed with fresh material, the fresh sieve quickly sulfides because the gas flow path is now uneven. Replace the full bed or use a guard bed to avoid this.
5. Using iron sponge with O2 in the gas stream. Iron sponge works by Fe2O3 + 3 H2S to Fe2S3 + 3 H2O. If free O2 is present (above 1000 ppmv), the iron sulfide re-oxidizes back to iron oxide and releases elemental sulfur, which then polymerizes and blocks the bed. Iron sponge is for O2-free streams only.
6. Forgetting COS in the H2S analysis. A gas with 0 ppmv H2S but 10 ppmv COS is still a 10 ppmv equivalent poison for the molecular sieve, because the COS hydrolyzes in the bed. Measure total sulfur, not just H2S.
7. Specifying a higher-grade sieve (LiLSX, specialty Y) for H2S service. LiLSX has even more lithium cation density than 13X and is more H2S-sensitive. Specialty Y zeolites can be dealuminated to improve H2S tolerance, but standard LiLSX is the wrong choice for sour gas service.

Relevant Standards for H2S and Molecular Sieve

If you need to cite published standards for your sieve specification or your H2S monitoring protocol, the following are the most relevant:

• ASTM D5504 - Standard Test Method for Determination of Sulfur Compounds in Natural Gas and Gaseous Fuels by Gas Chromatography and Chemiluminescence
• ASTM D4468 - Standard Test Method for Total Sulfur in Gaseous Fuels by Hydrogenolysis and Rateometric Colorimetry
• ASTM D5623 - Standard Test Method for Sulfur Compounds in Light Petroleum Liquids by Gas Chromatography and Sulfur Selective Detection
• ISO 19739 - Natural gas - Determination of sulfur compounds using gas chromatography
• ISO 6326 - Natural gas - Determination of sulfur compounds (multiple parts)
• UOP M-313 - Sulfur in Hydrocarbons by Oxidative Combustion with Detection by UV Fluorescence
• UOP 856 - Particulate, Liquid, and Gaseous Contaminants in Desiccant-Air Dryers
• GPSA Engineering Data Book - Section on Molecular Sieve Dehydration, including H2S effects
• API Specification 27 - Specification for High-pressure Molecular Sieve Adsorbents

For biogas and landfill gas service, the relevant standards are:

• ISO 20159 - Biogas - Determination of hydrogen sulfide content
• DIN 38414 - German standard for sulfur in sludge and biogas
• CJ/T 385 - Chinese standard for town gas odorization and H2S monitoring

Aluminaworld H2S-Tolerant Products - Data Sheets

For engineers ready to specify, here is the data sheet our customers use:

Full lot-level Certificate of Analysis is provided with every shipment, including H2S breakthrough capacity, particle size distribution, attrition, crush strength, and Si/Al ratio verified by XRF.

Frequently Asked Questions

Next Steps for Your Sour Gas Sieve Specification

If you are designing or operating a system where molecular sieve meets a sour gas stream, the data and field cases above should let you estimate sieve life, decide whether a guard bed is justified, and select the right sieve grade for the service. The key decision is to measure your actual H2S (and COS and mercaptan) feed concentration accurately before specifying the sieve, then design the guard bed for the worst-case inlet rather than the average case.

For H2S-resistant sieve grades, guard bed media, or a complete feed gas audit, contact the Aluminaworld technical team. We have supplied molecular sieve and activated alumina to sour gas operators in 60+ countries, including refinery dry gas dehydration units, EOR CO2 plants, biogas upgrading facilities, and natural gas processing plants across the EU, North America, the Middle East, and Asia.

Reach out via:

• WhatsApp: +86 133 2522 2240 (fastest, 12-hour reply, technical support in English and Mandarin)
• Email: barry@aluminaworld.com
• Sample request: 5 kg DD-13X-S R&D pack with full H2S breakthrough curve data, 10-15 day lead time
• Bulk orders: 500 kg MOQ, 20-25 day production for DD-series, FOB/CIF/CFR from Qingdao Port (80 km from our Zibo factory)
• Feed gas audit: Our application engineers can review your H2S, COS, and mercaptan data and recommend a guard bed + main bed configuration, free of charge for projects above 5 MT total sieve

Aluminaworld has manufactured molecular sieve under ISO 9001 quality control for 15 years, with SGS on-site audits and full Alibaba Trade Assurance coverage. Our DD-13X-S, DD-5A-Fe, and ZS-Series products are the result of 4 years of development work with refinery and biogas partners, and we are happy to put that experience to work on your next sour gas project.