Steam methane reforming (SMR) is the most common process for producing hydrogen-rich synthesis gas (syngas) from light hydrocarbons like natural gas, biogas and refinery feedstock.

Rising Hydrogen Demand

SMR is a cost-effective production method increasingly used to address the rising demand for hydrogen. Hydrogen is can be utilized as:

  • A reactive gas in a variety of hydrogenation processes
  • A feedstock in the production of fertilizers, fuels and peroxide products
  • An energy carrier

In 2016, the hydrogen generation market will generate an estimated $118 billion in revenue. It is projected to become a $152 billion market by 2021. There are numerous forces driving the expanding market for hydrogen:

  • Its status as a cleaner fuel than traditional competitors
  • Government regulations regarding desulfurization
  • Decreasing quality of overall crude oil sources

Steam Methane Reforming Process

In 2015, SMR technology grabbed more than one-third of the market by volume. It is an increasingly popular alternative to other hydrogen production methods like gasification, electrolysis and partial oxidation.

With SMR, an endothermic process captures syngas from feed materials. Super-heated steam, generated by both process heat and flue gases, is combined with the hydrocarbon feed in catalyst-filled reformer tubes. The steam/carbon ratio is managed to optimize the reforming process which occurs in the tubes. An external heat source causes hydrogen and carbon monoxide to form from the hydrocarbon/steam mixture according to these reactions:
Typically, burners are arrayed on the ceiling, between the rows of tubes, where they are fired downward. By precisely managing the steam/hydrocarbon relationship you can maximize Hydrogen yield. The goal is to simultaneously minimize the presence of methane and the accumulation of carbon deposits on the catalyst.

  • CnHm + n H2O => n CO + ((n+m)/2) H2
  • CH4 + H2O <=> CO + 3 H2
  • CO + H2O <=> CO2 + H2

In the final purification process, pressure swing absorption (PSA) is employed to absorb impurities from the syngas stream:
Industrial SMR plants can produce 99.9999 percent pure hydrogen. Plant capacities vary widely, from 1,000 Nm³/h to 200,000 Nm³/h and more. Recently, construction began on a large SMR plant in Baytown, Texas. When fully operational, the $400 million facility is expected to produce approximately 125 million standard cubic feet of hydrogen per day. It is expected to come online in 2018.

  • CH4+ H2O (Steam) = CO + H2 (Endothermic)
  • CO + H2O (Steam) = CO2 + H2 (Exothermic)

An alternative to SMR is auto-thermal reforming (ATR). Unlike steam methane reforming, ATR uses oxygen in an exothermic process to generate syngas. Methane is oxidized in a single chamber using either carbon dioxide or steam. When carbon dioxide is utilized, a 1:1 H2:CO ratio results. When steam is used, the H2:CO ratio is 2.5:1. The primary difference between SMR and ATR is that SMR uses no oxygen.

Growing Demand for Fuel Cells

Fuel cells are further accelerating demand for hydrogen. Fuel cell technology has come of age. For example, in 2017, Mercedes will produce a plug-in fuel-cell version of its GLC compact crossover.

Worldwide, the commercial fuel cell market is expected to grow to from $1.5 billion in 2016 to $4 billion in 2017. By 2022, the market is projected to expand further to $12 billion.

Fuel cell applications in power generation, motor vehicles, portable electronics and backup power systems will help to drive demand. The United States and Japan are expected to remain the largest markets for fuel cells during the next half-decade.

Fuel cells are highly attractive power sources due to:

  • Low carbon emissions
  • Relatively quiet systems
  • Space-saving systems (compared to other clean energy sources)
  • Rapidly expanding demand for clean, portable power sources

Researchers have explored possibility of on board SMR in motor vehicles, but thus far the process is not viewed as a practical alternative. Nonetheless, researchers are intrigued by the possibility of replacing on board high-pressure hydrogen tanks with relatively more benign methane tanks.