Vesihöyrymuunnos

Vesihöyrymuunnos, also known as steam reforming, is a process used to produce hydrogen gas and carbon monoxide from hydrocarbons, primarily methane, by reacting them with steam at high temperatures. This endothermic reaction typically occurs in the presence of a catalyst, such as nickel, in a specialized furnace. The general chemical equation for steam reforming of methane is CH4 + H2O → CO + 3H2.

The primary application of vesihöyrymuunnos is in the industrial production of hydrogen. Hydrogen is a crucial component in various chemical processes, including ammonia synthesis for fertilizers, methanol production, and petroleum refining. It is also gaining importance as a clean fuel source, with hydrogen fuel cells offering a way to generate electricity without greenhouse gas emissions.

The process involves several stages. First, the hydrocarbon feedstock, often natural gas, is purified to remove sulfur compounds that can poison the catalyst. Then, it is mixed with steam and preheated before entering the reformer tubes. After the reforming reaction, the resulting syngas (synthesis gas) mixture of hydrogen and carbon monoxide undergoes further processing. This typically includes a water-gas shift reaction, where carbon monoxide reacts with steam to produce more hydrogen and carbon dioxide (CO + H2O → CO2 + H2). Finally, the carbon dioxide is usually removed through a separation process, such as pressure swing adsorption or amine scrubbing, leaving a purified hydrogen stream.

While highly effective, vesihöyrymuunnos is an energy-intensive process that currently relies on fossil fuels, making it a source of carbon dioxide emissions. Research is ongoing to develop more sustainable methods, such as using renewable energy for heating or exploring direct steam reforming of biomass.