Ammonia cracking performance: How to navigate catalyst choice and technology

As the world accelerates its transition towards cleaner energy sources, the ammonia cracking market is heading for significant growth. The success of this process, crucial for efficient hydrogen transportation, hinges on selecting the right catalysts and technology to optimize performance. By navigating these intricacies, exceptional efficiency in ammonia cracking can be achieved, paving the way toward a decarbonized energy future – and operational profitability.

Using ammonia as a method for large-scale hydrogen transportation is available, proven and viable. With its well-established infrastructure, scalability, and low-carbon production routes, ammonia is an ideal carrier for hydrogen over long distances. Currently, 20 million tons of ammonia are transported annually. The ammonia market is projected to grow threefold to 700 million tons per year by 2050, in alignment with the 1.5°C scenario, with over 200 million tons of this being transported globally for conversion back to hydrogen.

Is catalyst and technology choice really that tricky?

Despite the opportunities in ammonia cracking, two areas are often cited as challenging when it comes to assessing the potential profitability of a new operation – the choice of catalyst and efficiency of the technology. 

A frequent question is “which type of catalyst is best suited for the ammonia cracking process?” Some argue that traditional reforming catalysts are adequate, while others believe that noble metal catalysts are necessary for achieving an efficient reaction. This uncertainty makes it difficult for companies to make informed decisions and invest confidently.

The second challenge revolves around the technology itself—whether it is proven, optimized, and ultimately profitable. Concerns about bankability arise due to the perceived scarcity of commercial large-scale ammonia cracking units in operation. Additionally, the energy efficiency of the process and the conversion efficiency also come under scrutiny.

Luckily both catalysts and technologies for ammonia cracking have a significant, successful history at large-scale and have been continuously monitored and optimized over time.   

Three decades of industrial experience

Topsoe’s development of ammonia cracking technology began in 1978, initially aimed at heavy water production. In 1993, Topsoe built the largest ammonia cracking facility in Argentina, capable of cracking 2 x 2,400 MT per day of ammonia in two parallel lines. This experience - exceeding three decades - has enabled Topsoe to develop proven ammonia cracking technology, specialized materials for handling ammonia, and a strong catalyst offering. Decades of catalyst development and manufacturing experience have positioned Topsoe uniquely in the ammonia cracking industry. Building on this foundation, Topsoe launched the first large-scale ammonia cracking technology for commercial hydrogen production in 2022.

Crucial catalyst choice

From experience, the most effective catalyst for ammonia cracking is the iron-cobalt catalyst, such as Topsoe’s DNK-2R. This catalyst has proven its efficacy on a large scale over decades, offering high activity, durability, and reasonable cost. Another reliable option is the iron-based catalyst, typically used for ammonia synthesis; however, it performs best at low ammonia concentrations and is susceptible to poisoning at high concentrations.

While ruthenium-based catalysts offer high activity, their high cost makes them less suitable for industrial applications. Alternatively, Topsoe's tailored nickel-based ammonia cracking catalysts (DNK-20 Retake and DNK-30 Retake) provide techno-economic optimization for the Topsoe H2Retake™ ammonia cracking solution, offering a balanced approach to efficiency and cost.

Cracking process efficiency

Two key metrics assess ammonia cracking efficiency: conversion efficiency and energy efficiency.

Hydrogen conversion efficiency measures the hydrogen produced relative to the hydrogen in the original ammonia. Achieving 100% hydrogen efficiency means all ammonia is converted to hydrogen, with any losses or fuel use reducing this percentage. This would only be even theoretically possible if alternative energy input is provided to drive the cracking reaction.

Energy efficiency, on the other hand, measures the energy output with the hydrogen product  relatively to the total energy input in the form of ammonia, electricity and possible additional fuel. For real industrial plants there will always be some energy loss bringing the energy efficiency below 100%.

Using ammonia as fuel lowers hydrogen yield but provides a zero carbon-intensity hydrogen product if using zero carbon intensity ammonia. External fuels boost hydrogen yield but may lead to CO2 emissions, while the use of renewable electrical power to drive the reaction maximizes hydrogen conversion with zero carbon intensity.

Technology with a primary focus on efficiency

Efficiency is crucial to the economics and viability of ammonia cracking plants, and Topsoe’s H2Retake™ technology exemplifies this focus. H2Retake utilizes energy from the side-fired ammonia cracker to drive the decomposition reaction, preheat, and evaporate the raw feed with minimal waste. This efficiency is achieved through a streamlined design, optimized heat and off-stream integration, and careful catalyst selection.

The cost of ammonia feed is the primary expense in hydrogen production from ammonia cracking. H2Retake’s optimized energy and hydrogen efficiency ensure the best possible business case. The technology’s heat integration eliminates the need for cooling or steam-generating systems, reducing total investment costs. It can be implemented on a large scale, centralized near major hydrogen consumers, or in decentralized locations.

H2Retake optimizes ammonia cracking by pumping the liquid ammonia feed to a pressure above that needed for hydrogen delivery, then vaporizing and preheating it using heat from the hot process and flue gases. The innovative process layout removes the need for a steam system, cutting both cost and complexity.

Ammonia decomposes into hydrogen and nitrogen in an adiabatic pre-converter and a fired tubular cracker. The pre-conversion step in the process reduces the fired cracker's fuel demand and maximizes flue gas energy use. The well-proven fired cracker, a cornerstone of this technology, has been successfully implemented in Topsoe’s plants.

With streamlined design, optimized heat integration, and careful catalyst selection, H2Retake™ achieves an impressive energy efficiency of 96%, ensuring maximum energy utilization and minimal waste.

Ready to optimize your ammonia cracking operations? Contact us today and get started.