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- Title
粉煤灰基沸石分子筛的合成及应用进展.
- Authors
何光耀; 王 兵; 史鹏程; 鲍卫仁; 常丽萍; 黄张根; 王建成; 韩丽娜
- Abstract
A large amount of fly ash is produced in the process of coal combustion. The output of fly ash in China ranks the first in the world. Because the comprehensive utilization rate is only 70%,a large amount of fly ash is still in open storage,resulting in serious environmental pollution and waste of resources. It is of great practical significance to eliminate environmental pollution of fly ash and improve its resource utilization for the development of circular economy in China. The utilization of fly ash in China has gradually changed from the early extensive large-scale utilization to the fine high-value utilization. Since fly ash is rich in silicon and aluminum elements,the synthesis of zeolite molecular sieve from fly ash is a research hotspot in the high-value utilization of fly ash in recent years. In this paper,the synthesis and application of fly ash based zeolite from four aspects were discussed. Firstly,the formation,physical and chemical properties,hazards,treatment and utilization status of fly ash were introduced. Fly ash is a mechanical mixture of particles with different mineral compositions and forms. Its properties are related to the composition,origin and combustion mode of raw coal. The characteristics of fly ash are the key to its comprehensive utilization. Secondly,three main activation methods of fly ash were discussed,including mechanical activation,hydrothermal activation and alkali (salt) melting activation. Silicon and aluminum in fly ash mainly exist in the form of amorphous mineral vitreous,and its surface is a dense glass shell. The key problem in the synthesis of zeolite molecular sieve by fly ash is how to make silicon and aluminum fully activated and effectively utilized. Compared with mechanical grinding activation and alkali (salt) melting activation,hydrothermal activation has higher activation efficiency and lower energy consumption. In the third part,the hydrothermal synthesis methods of fly ash based zeolite were discussed. The direct hydrothermal synthesis method,alkali fusion hydrothermal synthesis method,microwave/ultrasonic hydrothermal synthesis method,crystal seed method and crystal transformation method were mainly introduced. The synthesis of zeolite from fly ash is generally based on hydrothermal synthesis process. The purity of the product can be improved by multi step hydrothermal treatment. the yield,crystallization rate and crystallinity can be improved by ultrasonic,microwave,alkali melting and seed addition. The interzeolite conversion method can greatly expand the framework type and acid sites of fly ash based zeolite,which is a more favorable preparation technology of fly ash based zeolite. Finally,the application of fly ash based zeolite was summarized. The application of fly ash based zeolite is still in the exploratory stage,which is mainly used in the field of environmental treatment,including the adsorption and removal of heavy metal ions in industrial wastewater,the adsorption and removal of air pollutants and the adsorption of greenhouse gas CO2.
- Subjects
CHINA; FLY ash; POLLUTION; COAL combustion; HYDROTHERMAL synthesis; MOLECULAR sieves; AIR pollutants
- Publication
Clean Coal Technology, 2021, Vol 27, Issue 3, p48
- ISSN
1006-6772
- Publication type
Article
- DOI
10.13226/j.issn.1006-6772.SW21032901