Natural Gas

Tuesday, August 12, 2025

Scavenger Spotlight: Hemiformal in H2S Removal

Discover how hemiformal compounds play a vital role in H2S removal. Learn about their chemistry, benefits, and applications.

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Q2 Technologies Team

Experts in H2S Scavenging Solutions

With decades of combined experience, the Q2 Technologies team specializes in innovative hydrogen sulfide (H2S) scavenging solutions for the oil and gas, wastewater treatment, and industrial sectors.

Understanding their Role in H2S Removal

In the world of hydrogen sulfide (H2S) treatment, scavenger chemistry continues to evolve to meet the growing demands for efficiency, safety, and environmental compliance. One family of compounds that has long played a crucial role—but doesn’t always get the spotlight—is hemiformal. In this post, we take a closer look at the history, chemistry, and industrial applications of hemiformal as H2S scavengers. 

A Quick Primer: What Is a Hemiformal?

A hemiformal is a type of hemiacetal formed from the condensation of formaldehyde (HCHO) with an alcohol (ROH), following the equilibrium reaction: 

HCHO + ROH ⇌ RO–CH₂–OH 

The resulting compound, RO–CH₂–OH, is known as a hemiformal. Structurally, it is characterized by a carbon atom bonded to both a hydroxyl group (–OH) and an alkoxy group (–OR), making it a hemiacetal. In this case, the aldehyde is formaldehyde. A common example is methoxymethanol (CH₃OCH₂OH). 

 

Unlike pure formaldehyde or triazine-based scavengers, hemiformals offer a unique balance of reactivity, stability, and handling safety. Their molecular structure makes them especially effective at reacting with nucleophilic species, such as hydrogen sulfide (H₂S), making them suitable for various industrial applications.

What is hemiformal used for in H2removal?
A hemiformal is used as safer, controlled-release formaldehyde sources in hydrogen sulfide scavenging. Itsideal for gas sweetening, water treatment, and temporary sour service.

Historical Context and Development

The use of formaldehyde derivatives in gas treatment dates back several decades. Early scavengers relied heavily on unmodified formaldehyde, which raised safety and regulatory concerns due to volatility and toxicity. This led to the development of more stable alternatives—hemiformal being one of them. Its ability to release formaldehyde in situ, under controlled conditions, offered a safer and more targeted approach for H2S mitigation. 

Over time, hemiformal gained popularity in applications where triazine scavengers were less effective, such as high-temperature systems or operations requiring reduced scaling tendencies. 

How a Hemiformal works as Scavenger

When introduced into a stream afflicted with H2S, the hemiformal decomposes to release formaldehyde, which then reacts with hydrogen sulfide to form stable, non-volatile byproducts such as thiomethylene glycol.  The reaction is typically fast and efficient, particularly in aqueous or mixed-phase environments. Unlike some traditional scavengers, hemiformal can maintain activity across a broad pH range and is less likely to generate problematic solids. When considering if hemiformal is the right product, certain operating conditions are reviewed, such as pH and temperature. 

Key Benefits:

  • Controlled formaldehyde release 
  • Lower vapor pressure and improved safety profile 
  • Broad applicability across liquid and gas-phase systems 
  • Reduced scaling in sour water stripping and other high-temp operations 
  • Hemiformal can make the scavenger safe for transport as it is a very stable compound 

Applications Across the Industry

Hemiformal is used in a variety of upstream and midstream applications, including: 

  • Gas sweetening systems 
  • Produced water treatment 
  • Crude oil storage and transport 
  • Sour water stripper overheads 
  • Temporary H2S mitigation during maintenance or turnaround

Its adaptability makes it especially useful in operations where system conditions fluctuate or where traditional triazine-based products may underperform. 

Considerations and Limitations

While hemiformal offers many advantages, it is not a one-size-fits-all solution. The rate of formaldehyde release can vary depending on formulation and environmental conditions. Additionally, while safer than raw formaldehyde, hemiformal must still be handled with care and appropriate PPE. 

For optimal results, formulation expertise and application-specific customization are key—something we at Q2 Technologies excel at delivering. 

The Q2 Advantage

At Q2 Technologies, we’ve been at the forefront of H2S scavenger innovation for over two decades. Our hemiformal-based products (such as Pro3®) are engineered to provide targeted, efficient scavenging with reduced environmental and operational impact. We work closely with clients to match the right chemistry to the right conditions—ensuring performance, compliance, and safety.

Looking to explore whether hemiformal is  the right fit for your operation?
Contact us to learn more about our tailored H2S solutions. 

Experts in H2S and Mercaptan Removal Solutions.

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Oil & Liquids: Increase the Value of your Barrels.

Pro3® & ProM® use breakthrough non-amine/non-glyoxal H2S and Mercaptan removal technology.

Reduce chemical use by 50-75% as compared to glyoxal and MEA-Triazine.

Allows crude shippers to save on transport costs by sweetening crude to meet pipeline specifications.

Immediately remove H2S from crude oil and meet pipeline spec.
Pro3® is used by Producers, Midstreamers, and Traders and approved by major terminals and pipelines.

Pro-Series for Oil & Gas

Oil & Liquids: Increase the Value of your Barrels.

Pro3® & ProM® use breakthrough non-amine/non-glyoxal H2S and Mercaptan removal technology.

Reduce chemical use by 50-75% as compared to glyoxal and MEA-Triazine.

Allows crude shippers to save on transport costs by sweetening crude to meet pipeline specifications.

Natural Gas: Unlocking Gas MCFs.

H2S & Mercaptan Scavenger and MEA-Triazine Manufacturers.

Proprietary H2S scavenger blends engineered to reduce solids formation in scrubbers.

Continuous gas treating equipment that prevents H2S scavenger to become overspent.

Environmental

Keeping Our Planet Green.

Since 2001, we bring our experience to control H2S and odor with environmentally friendly processes in the Wastewater, Pulp & Paper, Landfill Gas, and Biogas Digester industries with Enviro-Scrub® and Enviro-Scrub® Bio product lines.

Q2 Technologies leads the industry in pairing real-time H2S testing with precise H2S dosing treatments – all automated.

 

We remove H2S from millions of barrels with Pro3®. Immediately remove H2S from crude oil, meet pipeline spec.

Our Process

Easy Onboarding & System Setup:
  • Our team of experts collaborates with you to know your specific needs – understanding your crude oil characteristics and meeting commercial thresholds.
  • We design a customized Pro3® treatment plan for optimal H2S removal.
  • In many cases we even provide the equipment and get your team up-to-speed on the Pro3® system.
Easy Onboarding & System Setup:
  • Pro3® is continuously injected into your crude oil stream, effectively rendering out H2S.
  • Real-time data on H2S readings, injection rates, and tank levels is available for complete transparency.
  • You, your control room, or field operators can remotely monitor and adjust pump settings through our secure/encrypted user-friendly web-based app.
Verified Results & Streamlined Operations:
  • Pro3® ensures consistent and reliable H2S removal, allowing you to meet pipeline specifications every time. However, dealing with mercaptans in your crude can be a challenge—see how to tackle this issue effectively here With recent geopolitical events impacting crude oil markets, H2S removal has become even more critical for stability and supply chain efficiency. Read more about its role in global energy security here.
  • Our process significantly reduces chemical usage compared to traditional methods, leading to substantial cost savings. With shipping costs surging, strategic cost-cutting is essential for staying competitive—discover how to maximize your barrel’s value here
  • Pro3® offers a fully automated and turnkey solution, minimizing operational burden and maximizing efficiency.

See how we are fundamentally changing the treatment of H2S with Pro3®. Our unique Hydrogen Sulfide removal systems can be highly automated and remotely controlled for maximum operational flexibility

Benefits of our H2S scavenger chemicals:

Lower your lease operating expense, reduce chemical use by 50-75% as compared to glyoxal and MEA triazine

Pro3® non-amine scavenger increases the value of your barrels, leads to better market optionality

Pro3® provides safety & protects assets

Pro3®® is scalable From

1

Wellheads

2

Terminal

3

VLCCs

Environmental

Keeping Our Planet Green.

Since 2001, we bring our experience to control H2S and odor with environmentally friendly processes in the Wastewater, Pulp & Paper, Landfill Gas, and Biogas Digester industries with Enviro-Scrub® and Enviro-Scrub® Bio product lines.

Pro3® H2S Removal for Crude Oil & Liquids

The Pro3® chemical process is used to treat millions of barrels of crude oil and liquid hydrocarbons every month throughout major US basins with an increasing global footprint. Our team of experts will work with you to ensure we meet your commercial, operational, and safety requirements in regards to Hydrogen Sulfide (H2S) and mercaptans. You’ll be able to have a complete Hydrogen Sulfide removal system

FAQs

It is a non-amine and non-glyoxal H2S removal technology, making it safe for refineries and pipelines.

Triazine-based treatment has been the go-to solution for many Producers, Midstreamers, and Refiners. But for some, implementing new technology such as non-triazine products has positively impacted their operations and has lowered their costs in their H2S removal efforts. Is one better than the other? That all depends on your use case and process conditions. Read more details here in our Triazine Vs. Non-Triazine blog.

We treat millions of barrels of crude and condensate and are successful in H2S removal to less than 10 ppm.

H2S in the oil and gas industry is very common. H2S removal products with Pro3® allows for Producers/Midstreamers to have safer operations and increase reliability. H2S compliance allows for safer transportation via pipelines which also allows for a better netback price of the barrels.

Who we are

We are a leading manufacturer of H2S & Mercaptan scavenger chemistries including MEA-Triazine. We have over 20 years H2S and mercaptan removal experience in the Oil & Gas, Pulp & Paper, Wastewater, Landfill Gas, and Digester Biogas industries.

Who we are

We are a leading manufacturer of H2S & Mercaptan scavenger chemistries including MEA-Triazine. We have over 20 years H2S and mercaptan removal experience in the Oil & Gas, Pulp & Paper, Wastewater, Landfill Gas, and Digester Biogas industries.

Who we are

We are a leading manufacturer of H2S & Mercaptan scavenger chemistries including MEA-Triazine. We have over 20 years H2S and mercaptan removal experience in the Oil & Gas, Pulp & Paper, Wastewater, Landfill Gas, and Digester Biogas industries.

Who we are

We are a leading manufacturer of H2S & Mercaptan scavenger chemistries including MEA-Triazine. We have over 20 years H2S and mercaptan removal experience in the Oil & Gas, Pulp & Paper, Wastewater, Landfill Gas, and Digester Biogas industries.

Reduce chemical use by 50-75% compared to conventional H2S scavengers.
Receive better net back pricing
Optimize operation through automation and turnkey process.
Crude Oil & Liquids - Pro3®
H2S Removal in Crude from Marine Tankers

– $10K per month chemical savings by using Pro3®
– Deliveries cut by 50%
– Millions of barrels treated and hundreds of tankers and barges in spec.

Crude Oil & Liquids - ProM®
Mercaptan Reduction in Condensate Splitter Feedstock

– ProM® Chemistry allowed customer to meet mercaptan specifications that MEA-Triazine was unable to reach.

Crude Oil & Liquids - Triazine
Amine Treater Regenerator Vent Scrubber

– H2S level reduced so that air can be discharged into atmosphere using Triazine.
-This continuous system has produced substantial economic benefits for the customer.