Gasoline from CO2
Gasoline is a hydrocarbon consisting of carbon and hydrogen in various proportions. Gasoline or petrol is a petroleum derived liquid used in internal combustion engine as fuel obtained by the fractional distillation of petroleum. Traditionally gasoline was produced from crude oil but in recent times handful of companies and scientists are finding ways to convert the chief GHG emitter CO2 into gasoline and other transportation fuels. While these initiatives are in early stages of development, researchers are confident of unveiling the prototypes that could lead to commercial roll outs. If found successful, such initiatives could reduce dependence on petroleum based products as well as renewable fuels such as corn ethanol that compete with food supplies. Scientists have demonstrated long back that CO2 can be used as feedstock for the production of fuels by breaking it apart and combining the carbon atom with hydrogen. Those are the building blocks of hydrocarbons such as oil and gas. The production of gasoline from CO2 is a simple chemical reaction. Gasoline when burned produces carbon monoxide, water and energy. The carbon monoxide is oxidized in a catalytic converter to produce CO2 and a little more energy. To produce gasoline from CO2, the above reaction has to be reversed. The CO2 has to be split to obtain carbon which on reacting with hydrogen (obtained from water) produces a hydrocarbon mixture methanol, which on further refining produces gasoline or jet fuel. The above reaction need excess amount of energy which makes the process inefficient and economically unfeasible.
The break down of CO2 takes place at high temperature and pressure and hence consumes huge amount of energy. Scientists are finding ways to split CO2 at low temperature and pressure. The enzymes and catalysts that are used in the splitting reaction of CO2 are expensive and hence add up to the cost making it economically unfeasible. A company has been successful in inventing a polymer shell that protects these expensive enzymes and catalysts that can be recycled many times. The same technology can be used to extract hydrogen from water, avoiding the need for energy-intensive hydrolysis.
The US Department of Energy (DOE) has been successful in obtaining a patent for converting CO2 to gasoline directly. Previously CO2 was converted to methanol which in turn was used in the production of gasoline. This invention relates to a process for producing synthetic fuels and chemical feedstock’s such as gasoline, methane and methanol from gaseous CO2 and H2 by extracting CO2 from the air with a sodium hydroxide solution. The resulting sodium carbonate solution is subjected to electrolysis in a three compartment electrolytic cell where hydrogen is formed at the cathode, oxygen at the anode and CO2 is released in the centre compartment. The hydrogen and the CO2 are subjected to catalytic reaction to form gasoline. The DOE obtaining a patent for this technology is a major breakthrough in the field of converting CO2 to useful products.
Another company Carbon Sciences is developing a technology to transform CO2 to liquid fuels like such as gasoline, diesel and jet fuel. In this process, CO2 directly reacts with methane derived from natural gas, land fills and other sources. This reaction takes place at a much lower pressure and temperature and hence to facilitate the reaction, a novel catalyst is used to produce gasoline from CO2.
According to the above reaction, for producing 3.5 tonnes of gasoline, 1 tonne of CO2 is used. The annual consumption of gasoline at present is 4 billion tonnes. If all the gasoline is produced from the above method proposed by the company substituting crude oil as feedstock, by using the CO2 captured from power plants and other industries, approximately 1 giga tonne of CO2 will be required to meet the global demand.