Solid acids are some of the most important heterogeneous catalysts that can replace environmentally harmful liquid acids in some important processes – hydrocarbon cracking, alkylation, and the decomposition of plastic waste and the conversion of carbon dioxide to fuel. Scientists have managed to solve two particularly important environmental problems with one development. The research results are published by the journal Nature.
The two best known solid acids are crystalline zeolites and amorphous aluminosilicates. Although zeolites are highly acidic, they are limited by their inherent microporosity, causing extreme diffusion restriction. While aluminosilicates are mesoporous, they suffer from low acidity and moderate stability. Thus, it is a synthetic task to develop and synthesize solid acids with acidity like zeolites and textural properties of aluminosilicates.
On the other hand, the main cause of climate change is carbon dioxide in the atmosphere, the level of which is increasing every day. The effect of global warming in terms of abrupt changes in weather conditions is already clearly visible and alarming. Thus, there is a great need to find ways to reduce carbon dioxide levels by separating it or converting it into fuel. Also, the growing amount of plastic waste has become a serious environmental problem. Most countries generate thousands of tons of plastic waste every day.
In the new work, the researchers addressed both of these problems in one go, developing nano-solid acids that convert carbon dioxide directly into fuel (dimethyl ether) and plastic waste into chemicals (hydrocarbons).
Using bicontinual microemulsion droplet techniques as a soft template, the scientists synthesized an acidic amorphous aluminosilicate (AAS) with a sponge nanomorphology that exhibits both zeolite (strong acidity) and amorphous aluminosilicate (mesoporous high surface area) properties.
Numerous studies have confirmed that the classification of new materials, due to its unique properties, borders between crystalline zeolite and amorphous aluminosilicate.
The new development could enable the development of solid acid catalysis to break down plastic as well as convert carbon dioxide into fuel. The process will take place under the conditions necessary to make it economically competitive.