How Topsoe makes ammonia: A technology guide

Ammonia is one of the most important molecules on the planet. It is a core feedstock for pharmaceuticals, plastics and fertilizer. And now, it is emerging as one of the most promising fuels and energy carriers of the diversifying fuel landscape and low-carbon future.

For instance, the maritime industry is actively developing ammonia-powered engines, while in large-scale industry, it is planned to be co-fired in thermal power plants to reduce emissions. It is also increasingly recognized as the most practical way to transport hydrogen across oceans due to its superior energy density. By 2050, global ammonia demand is projected to reach 688 million tonnes per year in a 1.5°C scenario – driven largely by new energy markets: shipping, power generation and hydrogen export. But ammonia's most familiar role remains the one closest to home: food. Roughly half the world's population is fed thanks to nitrogen fertilizers derived from ammonia. 

That scale brings both vulnerability and responsibility. Ammonia production is heavily concentrated in regions of geopolitical instability, and disruptions to natural gas supply routes – as recent tensions around the Strait of Hormuz have demonstrated – can send fertilizer prices soaring and threaten food security for millions. Diversifying how and where ammonia is produced is a matter of energy security and food security combined. 

Topsoe has delivered technology and catalysts for ammonia production for over 50 years and offers a portfolio of technologies covering the full spectrum: from conventional production, through low-carbon/blue routes, all the way to fully green ammonia. Here is how each technology approach produces ammonia.

Three methods of ammonia production

Making ammonia always ends the same way: nitrogen from the air is combined with hydrogen over a catalyst at high pressure and temperature (the Haber-Bosch process). The difference lies in how you make the hydrogen and how much CO₂ you emit doing it. Here are the three main methods.

Steam Methane Reforming (SMR)  

SMR with ATR is one of the two key reforming technologies whether you're making conventional grey or low-carbon blue ammonia. The difference between grey and blue is simply whether you add on carbon capture. The reason ATR, and specifically Topsoe's SynCOR™, dominates the blue ammonia conversation is that its chemistry makes CO₂ capture significantly easier, cheaper and more competitive than SMR. 

Currently, however, SMR dominates as the industry workhorse. Natural gas and steam react at 750–900 °C over a nickel catalyst in large tubular reactors to produce a hydrogen-rich gas. It's well-proven and available at a wide range of scales. Without additional CCS, this method produces grey ammonia, with the CO₂ produced released to atmosphere. If combined with CCS, blue ammonia is produced. But even though CCS can be added, SMR has an inherent challenge: the process relies on externally fired heaters, so CO₂ is split between the process gas and the furnace flue gas. Capturing the full stream therefore requires two separate capture systems, increasing cost and complexity. 

Topsoe offers several SMR variants for different needs: Standard SMR, which is the classic configuration, proven at industrial scale; HTCR (Haldor Topsoe Convection Reformer), a compact, modular design that recovers heat from flue gas rather than using a large furnace, ideal for smaller plants; and HTER (Heat-Exchange Reformer) and SMR-B, which are configurations that use surplus process heat to drive additional reforming, reducing fuel consumption and CO₂ footprint relative to hydrogen yield.  

Autothermal reforming – Topsoe’s SynCOR™

ATR takes a different approach. Oxygen, steam and natural gas are fed into a single compact reactor where partial combustion provides the heat for reforming, so no external furnace is required. Topsoe’s proprietary ATR technology, SynCOR™, is the cornerstone of Topsoe’s blue ammonia offering and is designed for very large, single‑train plants. 

A key differentiator is its very low steam‑to‑carbon (S/C) ratio of ~0.6, which is around five times lower than conventional SMR, which reduces steam demand and enables smaller equipment and lower overall cost. At mega‑scale, SynCOR™ supports single‑train capacities up to ~820 kNm³/h of H₂ (with the largest operational reactor at ~500 kNm³/h), helping deliver very competitive economics. 

Combined with CCS, SynCOR™ really shines on capture readiness: because there is no furnace and no flue gas, virtually all carbon is concentrated in the high‑pressure process gas, making CO₂ capture simpler and typically cheaper. In many configurations, ~88% of the carbon can be captured directly from the process gas with no additional “second system,” and with further capture technology total CO₂ removal can exceed >99% – without needing flue‑gas capture – resulting in exceptionally low carbon intensity for low‑carbon hydrogen/ammonia production. 

Whichever reforming technology is used, blue ammonia requires efficient carbon capture. Topsoe works with all major CO₂ removal approaches and offers a single license covering reforming, CO₂ removal, and ammonia synthesis, with CO₂ capture technology sub‑licensed from leading providers.

eREACT™: An electrified approach

eREACT™ is Topsoe's electrified steam methane reforming technology – a clever bridge between the fossil and renewable worlds. Instead of burning fuel to heat the reforming reactor, eREACT uses electricity to heat a catalytic reactor directly, eliminating combustion and its associated flue gas emissions entirely. 
 
This has some important advantages. Because there is no combustion, there is no flue gas CO₂ to worry about, so all the carbon is in the process gas, making it highly suitable for CCS. The reactor is far more compact than a traditional SMR furnace, thanks to its high energy density and it is particularly well-suited to small and medium-scale blue hydrogen and ammonia production, especially where electricity costs are competitive.

Green ammonia – Powered by renewables

Green ammonia skips fossil fuels entirely. Hydrogen is produced by splitting water using renewable electricity – a process called electrolysis – then fed directly into the Haber-Bosch ammonia loop. No CO₂ is produced at any stage. 

Topsoe's proprietary Solid Oxide Electrolyzer Cell (SOEC) operates at high temperatures, which makes the electrolysis reaction thermodynamically more favourable. The result: 20-30% higher efficiency than alkaline or PEM electrolyzers when paired with waste-heat technologies. After more than 30 years of development, Topsoe's SOEC is regarded as the most efficient electrolyzer on the market. 

Unlike low-temperature electrolysis technologies, SOEC is built on abundant, non-noble materials, meaning it avoids the supply chain risks and cost pressures associated with scarce or geopolitically sensitive minerals. It can also electrolyze CO₂ alongside water, producing carbon monoxide for use in synthetic fuels, a capability that extends its relevance well beyond ammonia production. 

Green ammonia is increasingly recognized as one of the most promising pathways for fuel diversification and the clean energy transition. As renewable electricity capacity grows and electrolyzer costs come down, green ammonia is well positioned to scale, serving fertilizer markets, clean fuel applications and the emerging hydrogen export economy simultaneously. 

This is the second article in our Ammonia for Fertilizer series. 
Read our earlier article: Getting from gas to grain – how are ammonia-based fertilizers made?