Technical Progress of Natural Gas Chemical Industry

Since 1920s, natural gas chemical industry has been achieving stable and rapid developments because of its unique advantages of technology and economy. In the 21st century, environmental protection has been valued by more and more countries worldwide, and natural gas is regarded as a kind of resource in a high grade which can be developed in an environment-friendly way. Therefore, in order to protect the environment and obtain sustainable economic development, it is the best choice for countries and governments in the world to greatly develop natural gas chemical industry. It is estimated that the quantity demand of natural gas will increase from the present 2.6 trillion to 4.9 trillion in 2020, and the ratio natural gas takes up in energy structure will increase from 24.5% in 2000 to 51% in 2040, which means natural gas will become the first energy beyond petroleum and coal.

According to transformation ways, the chemical application of natural gas can be divided into two categories: direct method and indirect method. Direct method is to obtain products like ethane, carbinol and arene through direct-reaction oxidization of natural gas; indirect method is to produce chemicals like clean oil, carbinol and low carbon olefin through processing synthesis gas produced by natural gas at the beginning.

It is possible for direct method to gain more profits because of its short production process. Therefore, direct method is one of study focuses of natural gas chemical industry in the future, whose main production direction is to produce chemicals like carbinol, formaldehyde, ethane and arene through direct oxidization of methane. However, during the production process, there are too many by-products, and the reactions are difficult to control. So the productivity of objective products is relatively low, and direct method is still on the stage of laboratory research. While during the process operated by indirect method, methane will be first made into synthesis gas and then made into liquid fuel and some other chemicals. At present, indirect method has been a main technological line of the application of natural gas chemical industry.

Nowadays, there are three different lines in direct method. They are the direct productions of carbinol and formaldehyde made of natural gas, ethene through coupled oxidation of natural gas, and arene made of natural gas under the oxygen-deprived condition.

Indirect method is to transform natural gas into synthesis gas and further synthesize synthesis gas into other chemicals. The cost of synthesis gas takes up about 60% of the whole investment and cost. Therefore, the development of new technology of synthesis gas plays a crucial role in increasing the economic benefits in the application of natural gas chemical industry. In order to reduce the energy consumption of producing synthesis gas and accelerate the flexible adjustment of hydrogen-carbon ration, several kinds of production technologies of synthesis gas have been developed by researchers and scholars. There are three various stages of technology of applying synthesis gas at home and abroad. The technology of producing carbinol and synthesis ammonia by natural gas is mature; the technology of producing liquid fuel by natural gas is growing; and the technology of producing dimethyl ether and olefin by natural gas is to be industrialized.