Preparation method of mesoporous silica

Abstract

The invention discloses a preparation method of mesoporous silica, which comprises the following steps of (1) breaking and sieving raw materials containing amorphous silica, (2) soaking the broken and sieved raw materials with an inorganic acid solution, filtering, and separating filter residues from acid liquid, (3) adding the filter residues into a sodium carbonate solution or a potassium carbonate solution, heating, stirring for reaction for 1-8h, and filtering, (4) adding a structure-directing agent into a filtrate, (5) stirring, ageing, filtering, returning the filtrate to Step (1) for recycling, and conducting vacuum drying on a filter cake, and (6) sending the dried filter cake into a muffle furnace, conducting temperature programming under nitrogen protection, removing the structure-directing agent or sending into a microwave digestion device for digestion, and removing the structure-directing agent. According to the preparation method, as the raw materials containing amorphous silica are directly adopted as a silicon source for producing mesoporous silica and an alkali solution is recycled, the reaction time is shortened, and the production cost of mesoporous silica is greatly lowered.

Description

technical field [0001] The invention relates to a method for preparing silicon dioxide, in particular to a method for preparing mesoporous silicon dioxide. Background technique [0002] Mesoporous materials refer to a new class of materials with pore diameters ranging from 2 to 50nm. Because of their abundant interconnected pore systems, they have great potential application value in mass transfer and separation. The synthesis of mesoporous materials has attracted much attention. focus on. For a long time, the preparation of mesoporous silica often needs to use expensive silicon alkoxide and silicate as the silicon source, and the cost is extremely high. Searching for cheap and easy-to-obtain silicon sources and developing corresponding synthetic process routes is one of the focuses of researchers at present. [0003] In order to solve this problem, researchers first used relatively cheap sodium silicate (water glass) as a silicon source to synthesize hybrid mesoporous sil...

AI Technical Summary

Problems solved by technology

From these two methods, whether sodium silicate (water glass) is directly used as a silicon source, or NaOH is used to react with amorphous silicon dioxide in the raw material to form a sodium silicate silicon source, before aging It is necessary to add hydrochloric acid to precipitate silica to form a mesoporous material skeleton. This process not only consumes hydrochloric acid and NaOH, but also generates waste brine containing NaCl, which not only increases the cost but also affects the environment.

In addition, Hou Guihua et al. have reported that rice husk ash was obtained by high-temperature pyrolysis after acid boiling and removal of impurities from rice husk, and then using rice husk ash (RHA) as raw material in acidic and alkaline environments with CTAB as the structure-oriented The MCM-41 mesoporous material with high specific surface area was synthesized by using a high specific surface area. This research pioneered the process route of synthesizing mesoporous material from rice husk, but the synthesis route is to directly add RHA to the reaction system. On the one hand, RHA will leave organic matter and carbon. On the other hand, the silicon source capable of forming new mesoporous frameworks only accounts for a small fraction of the RHA silicon species, so the quality of the obtained mesoporous materials is not high (see Synthesis of ordered mesoporous silica materials using rice hull ash as silicon source Research, "Journal of Materials Science and Engineering", 2006, Vol. 24, No. 4)