Sewer gas to hydrogen fuel conversion a possibility through new technology

New study shows how to turn stinky, toxic gas to fuel

A new study has shown that it is possible to convert “sewer gas” into clean hydrogen fuel using a chemical process.

Published in the journal ACS Sustainable Chemical Engineering, the study shows how the stinky hydrogen sulfide can be converted to hydrogen gas which in turn can be used as clean fuel. Hydrogen sulfide is an industrial byproduct and is also emitted from manure piles and sewer pipes.

Researchers have shown in the new study how it is possible to use relatively little energy and a relatively cheap material – the chemical iron sulfide with a trace amount of molybdenum as an additive to convert this rotten eggs-like smelling hydrogen sulfide into hydrogen.

Hydrogen sulfide is highly toxic that not only corrodes pipes but is also harmful for people who come in contact of this gas. For years scientists have been looking for ways to convert hydrogen sulfide into something that is not so harmful, preferably valuable.

The study is built on previous work by the same research group using a process called chemical looping, which involves adding metal oxide particles in high-pressure reactors to burn fuels without direct contact between air and fuel. The team first used chemical looping on coal and shale gas to convert fossil fuels into electricity without emitting carbon dioxide into the atmosphere. The initial process used iron oxide to break down the fossil fuels.

The researchers later applied the concept to hydrogen sulfide and invented the SULGEN process, which converts hydrogen sulfide into hydrogen. The researchers found that the pure chemical, iron sulfide, didn’t perform well at the large scales needed for industrial use, Qin said. The research team has been trying to identify other inexpensive chemicals that could catalyze that transformation in higher quantities. This study shows that introducing a trace amount of molybdenum into iron sulfide might be an attractive option.

That material is relatively inexpensive and easy to acquire, making it an attractive option for larger-scale operations.

Transforming this toxic gas into hydrogen fuel creates an alternative oil and gas, which are major contributors to climate change, the researchers said.

For this most recent study, the researchers found that molybdenum improves the breakdown of hydrogen sulfide, splitting it into two parts – hydrogen fuel and sulfur.

This work is early in the scientific process – the researchers showed that the process worked in the lab; tests at the industrial level are forthcoming.

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