Can China's Chemicals-from-Coal Sector Become Environmentally Sustainable?
1:12 PM MDT | June 9, 2011 | By ALEX SCOTT
As reported by CW this week from Süd-Chemie’s ‘Defining the Future’ technology symposium in Beijing, Chinese chemical companies are developing a huge pipeline of projects for generating chemicals and fuels from the country’s most abundant feedstock; coal. Whether they can do this in an environmentally responsible manner – especially within the context of global warming - remains an unknown, but as argued here, there are grounds for optimism.
Despite what coal marketers would have us believe, there is no such thing as ‘clean coal’. Not yet. But efficient catalytic processes, as well as Carbon Capture and Storage (CCS) systems could ensure that the environmental impact of using coal to make chemicals and fuels is markedly reduced to a socially acceptable level. China’s raft of large scale coal-to-chemical projects are already being built, however, while CCS technologies at commercial scale have yet to be proven. There is also a question mark over how much CO2 from Chinese coal-to-chemical processes could be stored.
As XiangHong Cao, chemistry professor at the Chinese Academy of Engineering and a member of Sinopec’s scientific committee, told delegates at Süd-Chemie’s symposium, China’s chemical manufacturers are entering a “challenging” phase where they will seek to meet the country’s burgeoning demand for materials and energy in an age when domestic oil reserves are dropping, combined with a second challenge of meeting new tougher Chinese environmental performance standards.
Cao is convinced that the Chinese companies developing chemicals from coal “are trying to deal with the CO2 emissions” that their manufacturing will generate. More efficient processes for coal-to-chemicals synthesis are being developed, but new technologies also must be introduced, he says. “There need to be improvements in current processes, with the development of novel catalysts and fixed-bed hydrogenation technologies. There is also a need to limit residues for coking capacity and reduce residue coking processing capacity on a step-by-step basis.” Another requirement is the improved environmental performance of fuels from coal and other feedstocks. “Naphtha cracking is going to be replaced by new feedstocks. The problem is that some coal properties are not ‘good enough’ and so we have to produce methanol first and propylene – or other chemicals – second. We have to be sure that we are not going to pollute the environment,” Cao says.
Methanol-to-olefins (MTO) and methanol-to-propylene (MTP) processes also use large volumes of water. This is another environmental parameter that in China producers must take into account. “We have to consider the local environment,” Cao says. The significance of this final point was made all the more pertinent this week, with one Chinese newspaper reporting that thousands of people are on the move in China because of a lack of available drinking water caused by drought.
Technology developers including Lurgi and Süd-Chemie were among those at the Beijing symposium that told delegates they are confident that processes for chemicals from coal can be made environmentally sustainable. “Coal-to-chemicals can be [developed] in a profitable way but also in an environmentally acceptable way,” Günter von Au, outgoing chairman of Süd-Chemie, told delegates in an opening address at the Beijing symposium.
Ulf Herrlett, v.p./engineering and technology at Lurgi, during a presentation at the symposium reeled off a series of novel technologies that will enable efficient synthesis of coal-to-chemicals. Among them is Lurgi’s methanol technology, which can enable the use of coal to make a range of chemicals including propylene, he says.
However, even with Lurgi’s expertise in processing technology and Süd-Chemie’s contribution as the process catalyst provider, the coal-to-propylene process “has slightly higher CO2 emissions” than its crude oil-derived process equivalent, Thomas Würzel, director/engineering and construction for Lurgi told CW in a question and answer session following his presentation. The underlying reason is that it requires more steps to get from the coal to the propylene than does oil to propylene, he says.
In all likelihood, CCS in the next 10 years will become technologically viable and will be applied in many countries – in part because so many world-class chemical and petrochemical companies, and governments, are investing in it and can’t afford to let it fail. It's also a given that the clever chemists developing novel catalysts at Süd-Chemie and other leading catalyst firms will ensure that catalytic processes become more efficient. The real uncertainty is whether the Chinese government will consider it a necessity to make its coal-to-chemicals producers apply expensive CCS systems to their plants in the first place. Until that day comes, clean coal-to-chemicals and fuels will continue to exist only as an idea.
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