Synthesis Of Mesoporous Aluminosilicates With High Stability By Binary Composite Templates/mother Liquor Recycling

Mesoporous aluminatesilicates(MAs),which is an active functional component of FCC catalysts,play an important role in the process of heavy oil catalytic cracking.Our research group reported that MAs with high hydrothermal stability was obtained by introducing the primary/secondary building units of microporous zeolite into the mesoporous wall by precursor assembly strategy.The process had successfully realized the industrial production and application of MAs in the world for the first time,and hydrothermal stability of products was equivalent to that of USY.However,this method suffers from low utilization efficiency of the template and large wastewater discharge.In order to solve these problems,the following studies were carried out in this paper.1.Polyethylene glycol(PEG)formed hydrogen bonds with water to reduce the surface tension of the solution;meanwhile,some PEG molecules could enter the interior of P123 micelles and interact with PEO.It enhanced the hydrophilicity and dispersibility of the micelles,increasing the activity of the micelles in the high concentration system,and thus reduced the consumption of the template and water.In this process,the template utilization efficiency and the water consumption were 1.05 g P123/g zeolite and 20.8 g H2O/g zeolite,respectively.Compared with conventional method,P123 utilization increased by about 26.6%,water consumption decreased by about 51.6%,and synthesis cost decreased by about 18.2%.The total specific surface area(SBET)and total pore volume(VTotai)of the sample were 695.0 m2.g-1 and 0.79 cm3.g-1,respectively.The retention ratios were 36.9%and 53.2%after hydrothermal treatment,respectively.In addition,the effects of different concentration and molecular weights of PEG on the structure and physicochemical properties of samples were also investigated.2.P123-AES composite micelles were obtained by hydrophobic force between the alkyl chain of sodium alcohol ether sulphate(AES)and the PPO segment of P123.Meanwhile,the synergy of AES ether bond and polar head(—SO4-)induced water molecules moving closer to the composite micelles,which enhanced the hydrophilicity and dispersibility of the micelles.This strategy was conducive to the assembly of precursors around micelles,which guided the synthesis of MAs with high hydrothermal stability.In this process,the template utilization efficiency and the water consumption were 1.0 g P123/g zeolite and 19.9 g H2O/g zeolite,respectively.Compared with conventional method,P123 utilization increased by about 30.0%,water consumption decreased by about 53.7%,and synthesis cost decreased by about 24.9%.The total specific surface area(SBET)and total pore volume(VTotai)of the sample were 693.5 m2.g-1 and 0.89 cm3.g-1,respectively.The retention ratios were 38.6%and 48.3%after hydrothermal treatment,respectively.3.Mother liquor recycling method could realize the obtaining of MAs by recycling the reactants(such as silicon,aluminum,P123,water,etc.)remaining in the mother liquor,which greatly reduced the consumption of the template and water.However,as the mother liquor cycles increased,the enhanced concentration of solution would lead to the decreased dispersibility and subsequent agglomeration of P123 micelles.This seriously hindered the assembly of inorganic species around the micelles,resulting in poor orderliness and hydrothermal stability of the sample.AES was introduced into the mother liquor recycling process through the action of AES and P123,enhancing the hydrophilicity and dispersibility of the micelles.By combination of binary templates and mother liquor recycling,MAs with high hydrothermal stability was obtained effectively.In this process,the template utilization efficiency and the water consumption were 0.80 g P123/g zeolite and 15.0 g H2O/g zeolite,respectively.Compared with conventional method,P123 utilization increased by about 42.0%,water consumption decreased by about 65.1%,and synthesis cost decreased by about 23.0%.The total specific surface area(SBET)and total pore volume(VTotal)of the sample were 665.4 m2.g-1 and 0.77 cm3.g-1,respectively.The retention ratios were 32.1%and 45.4%after hydrothermal treatment,respectively.In summary,MAs with high hydrothermal stability was synthesized by binary composite templates/mother liquor recycling,which significantly reduced the synthesis cost and the wastewater discharge.This novel strategy sheds a light on the industrial application of MAs.