Chemical Industry Structure From The Complex Network Perspective

Chemical industry has the best performance on material utilization in anthropogenic sphere, but it has also caused environmental problems due to the great amount and diversity of chemical products. It is important to identify and manage chemical industry structure as well as the intriguing links among numerous chemicals. Therefore, based on complex theory, a network of chemical industry in 1970s constructed from chemical reactions was analyzed and compared with the studies on cell networks and ecological networks to identify the structural and dynamical features of its material flow patterns. Meanwhile, two networks, constructed from process flow diagram representing a case in 1970s and a case in recent years seperately, were analyzed and compared, from which the differences in structure and evolutionary principles were identified.The results have shown that, similar to biological systems, material production patterns in chemical industry are hierarchically organized units named Feed-forward loop, Bi-fan and Bi-parallel, which reflect the inner feature of chemical production and keep unchanged through the development of chemical industry. In the evolutionary processes of chemical industry, fierce competitions do not exist in processes using same feedstock but in those producing same products, which have given birth to homogeneous production and inhomogeneous utilization. After 30 years advancement or so, chemical industry has fitted small world model better and thus shown better synchronizability despite its larger size. There is better structural efficiency of material utilization, since fewer processes are needed from basic feedstock to final products. However, it seems that there is no chance for the structural efficiency in chemical industry to go beyond that in food webs due to the lack of Three-chain unit. The stability is less important in chemical industry than in biological or ecological industries, as it decreases with the connectance among products. The small world and error-tolerance characters of chemical industry enable that it could be adjusted by economic and political stimuli, which should follow the structural and evolutionary principles in chemical industry. The comparison between industrial and natural systems based on complex networks offers a new approach to the ecological metaphor in industrial ecology. It also offers an empirical case to complex system theory. However, for better management of chemicals and the fulfillment of sustainable development in chemical industry, it is important to construct larger network database and study the building mechanism of structural units.