Chinese scientists have developed a new oil-refining technique that they say can reduce energy consumption by roughly 90 per cent, potentially lowering production costs and emissions while enabling refineries to extract greater value from crude oil.
The process, developed by researchers at the Dalian Institute of Chemical Physics, replaces conventional distillation with what the team describes as “molecular refining” — a method designed to separate crude-oil compounds according to their molecular characteristics rather than relying primarily on differences in boiling points.
Crude oil cannot be converted directly into petrol or plastics. Refineries must first separate it into different components, making separation one of the most energy-intensive stages of refining. Conventional distillation repeatedly heats crude oil so that different compounds vaporise and condense, but the researchers say the approach is comparatively imprecise and consumes substantial amounts of energy.
The new technique operates at the molecular level, using chemical membranes to direct different compounds towards the production processes for which they are best suited. The approach is based on metal organic framework membranes, which contain specially designed pores and surface properties that allow them to act as highly selective molecular sieves.
Known as cascade membrane separation, the process begins by sorting molecules according to size. Although many of the compounds in crude oil appear similar, their molecular dimensions can differ by about 0.1 nanometre. A specially engineered membrane separates smaller straight-chain and single-branched alkanes, which are used to produce ethylene.
The remaining molecules present a more difficult separation problem because their size differences are less than 0.01nm. At this stage, the researchers use a second membrane whose surface chemistry is designed to recognise and distinguish between different molecules.
That membrane separates chemical aromatics, which are important intermediates for producing plastics, resins and fibres, from multi-branched alkanes and cycloalkanes, which are used to make petrol.
To achieve the required precision, the team employed a tannic acid micro-etching method that continuously adjusts the membranes’ pore size and surface chemistry for different sorting tasks.
The researchers tested the two membranes in series using a simulated light naphtha mixture containing 15 components. In laboratory experiments, the system separated the mixture into three groups of high-value products, achieving a recovery rate of between 85 and 90 per cent, according to the study.
The more significant result concerned energy consumption. Because the new method avoids the repeated heating, vaporisation and condensation required by conventional distillation, the researchers reported that it used around 91 per cent less energy than the traditional process.
If the laboratory results can be reproduced at industrial scale, the implications could extend beyond energy savings. A more selective refining process could reduce emissions and production costs while allowing crude oil to be separated more precisely into higher-value feedstocks for fuels and petrochemicals.
The findings were published last month in National Science Review. The researchers described their approach as a “graded sorting paradigm” that could provide a new platform for petrochemical refining by maximising value extraction while substantially improving energy efficiency.
The key test now lies beyond the laboratory: whether membranes capable of such precise molecular separation can be manufactured and operated reliably on the scale required by modern refineries.
