Preparation method of pervaporation layer-by-layer assembled membrane for gasoline desulfurization

Abstract

The invention provides a preparation method of a pervaporation layer-by-layer assembled membrane for gasoline desulfurization. The layer-by-layer assembled film is a multilayer composite film including three or more layers. The preparation method of the layer-by-layer assembled membrane comprises the following steps: S1, preparing a porous supporting bottom membrane; S2, forming a metal organic framework membrane, namely an MOFs membrane, on the bottom membrane in situ; and S3, coating the surface of the MOFs film with polyethylene glycol to form the composite film, namely the MOFs / PEG layer-by-layer assembled film. The metal elements contained in the inorganic particles used in step S1 are the same as the metal elements contained in the metal salt in step S2. The layer-by-layer assembledmembrane has a good sulfur-rich effect reaching 19.5 at most on sulfur-containing gasoline, is high in sulfur-rich factor and good in permeation flux being 3.583 kg / m<2>*h, and has a good industrial application prospect.

Description

technical field [0001] The invention belongs to the field of pervaporation membrane separation, in particular to a method for preparing a pervaporation layer-by-layer assembly membrane for gasoline desulfurization. Background technique [0002] The sulfur compounds in gasoline will cause serious air pollution. The sulfur compounds in gasoline will generate sulfur oxides after combustion, which will form acid rain and pollute the environment when discharged into the air. Many countries in the world today limit the sulfur content in gasoline to within 10ppm ; Therefore, in the face of increasingly stringent environmental protection standards, the production of ultra-low sulfur gasoline has become a standard requirement in the oil refining industry, and the improvement of gasoline desulfurization technology is a major research topic we have to face. Gasoline is a petroleum refined product composed of alkanes, a mixture of C5-C14 olefins and naphthenes, and aromatic compounds. ...

AI Technical Summary

Problems solved by technology

However, due to the significant difference in physical and chemical properties between inorganic particles and PEG polymer membrane materials, there are two important challenges in the preparation process of inorganic particle-filled PEG mixed matrix membranes. It is easy to form non-selective defects, which cannot exert the modification effect of inorganic particles on polymer membranes, and instead causes a decrease in the selectivity of membranes for small molecules. Therefore, researchers often use methods of increasing the thickness of mixed matrix membranes to weaken non-selective The selectivity decline caused by sexual defects, which also caused the increase of mass transfer resistance of small molecules, and the decrease of permeation flux; When the interaction force between the material-based film and the inorganic particles is too weak, it is easy to cause interface defects, resulting in a decrease in selectivity. If the interaction between the two is strong, the PEG molecular chain enters the pores of the inorganic particles in the presence of a solvent, which may block some The pores of inorganic particles make it difficult to give full play to the preferential adsorption of sulfur by inorganic particles, resulting in a low sulfur-enrichment factor. Therefore, designing and preparing inorganic particles with better compatibility with PEG-based membranes is also the key to improving their separation performance.

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