Emission-free conversion of natural gas to liquids

Scientists from CoorsTek Membrane Sciences, the University of Oslo and the Instituto de Tecnología Química (ITQ) have developed a new process to use natural gas as raw material for aromatic chemicals. The process uses a novel ceramic membrane to make the direct, non-oxidative conversion of gas to liquids possible for the first time — reducing cost, eliminating multiple process steps and avoiding any carbon dioxide emissions.

Direct activation of methane, the main component of biogas and natural gas, has been a key goal of the hydrocarbon research community for decades. But even when available for industrial conversions, the high stability of the methane molecule leads to energy losses associated with multistage processing in large chemical plants which use oxygen or steam to activate the methane in what is known as synthesis gas processing.

The scientists found that integrating a ceramic ion-conducting membrane into a reactor enables an increase in the productivity of industrially appealing processes which are otherwise impractical due to strong thermodynamic constraints. The resulting aromatic precursors, described in the journal Science, are source chemicals for insulation materials, plastics, textiles and jet fuel, among other valuable products.

“By using a ceramic membrane that simultaneously removes hydrogen and injects oxygen, we have been able to make liquid hydrocarbons directly from methane in a one-step process,” said Dr Jose Serra, a co-author on the study from ITQ. “As a bonus, the process also generates a high-purity hydrogen stream as a by-product.

“At a macro level it is really very simple — inexpensive, abundant gas in and valuable liquid out through a clean, inexpensive process. At a nanochemistry level, however, where molecules interact with catalyst and membrane at a temperature around 700°C, there were many factors to engineer and control in order to render just the specific valuable molecules needed to make the new process work.”

According to Dr Serra, the new process has the potential to transform the gas and petrochemicals industry. “With new ceramic membrane reactors to make fuels and chemicals from natural gas instead of crude oil, the whole hydrocarbon value chain can become significantly less expensive, cleaner and leaner,” he said.