Effect of Dealumination of Citric Acid-Modified Hβ Molecular Sieve on Hydroisomerization Performance of n-Hexadecane

6th Annual International Conference on Material Science and Environmental Engineering

材料科学;生态环境科学

Bai, Xuefeng^1^2 ; Wei, Xiaomeng^2 ; Liu, Yang^1 ; Wu, Wei^2

Institute of Petrochemistry, Heilongjiang Academy of Sciences, Harbin

150040, China^1

School of Chemistry and Material Sciences, Heilongjiang University, Harbin

150080, China^2

关键词: Acid concentrations;    Bi-functional catalysts;    Chemical absorption;    Hydro-isomerization;    Incipientwetness impregnation;    Physical adsorption;    Reaction temperature;    Relative crystallinity;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/472/1/012040/pdf
DOI  :  10.1088/1757-899X/472/1/012040

来源: IOP

【 摘 要 】

Hβ molecular sieves with SiO2/Al2O3 ratio of 40 were modified by citric acid dealumination (Hβ-Cn) and Hβ-Cn loading Pd (0.5 wt%) bifunctional catalysts(Pd/Hβ-Cn) were prepared by hydrothermal synthesis and incipient wetness impregnation. The structure, morphology, pore and acid properties of Hβ-Cn and Pd dispersion of Pd/Hβ-Cn were characterized using XRD, SEM, N2 physical adsorption, NH3-TPD and H2 chemical absorption. The skeleton structure of all Hβ-Cn was not damaged and their relative crystallinity increased somewhat after the treatment of citric acid. With the increase of citric acid concentration, the change of morphology,structure and pore properties of Hβ-Cn was very little, but the amount of weak acid, strong acid and total acid of Hβ-Cn, and Pd dispersion for Pd/Hβ-Cn decreased significantly. It was known from hydroisomerization perforamce of n-C16H34 that the hydroisomerization reaction temperature over Pd/Hp-Cn slightly rises under the condition of the same conversion of n-C16H34, but the amount of multi-branched iso-C16H34 over Pd/Hβ-Cn, especially Pd/Hβ-C2 (60.51%) and Pd/Hβ-C3 (57.84%) was much higher than that over Pd/Hβ (36.99%). This could be due to the remove of partial skeleton aluminum species with strong acid sites to effectively inhibit the further cracking of the muti-branched isomerized products.