Preparation Of Rice Husk-based Mesoporous Catalyst And Its Alkane Isomerization Performance

China is a big rice-producing country,and tens of millions of tons of agricultural waste rice husk is produced every year.Economical and efficient use of rice husk resources can not only reduce industrial costs,but also produce huge economic and environmental benefits.In this paper,high-purity NaP1 and MSOD zeolites were prepared by mixing rice husk as silicon source with aluminum source and alkali after roasting and crystallization.The method has low cost and simple process,and at the same time realizes the regeneration and utilization of agricultural waste.Through XRD,IR,SEM,TEM-EDAX,N₂adsorption-desorption,XPS,NH₃-TPD,TG-DTA and other characterization methods to analyze the sample crystal structure,microscopic morphology and metal dispersion,and use n-heptane The isomerization reaction were used as a probe to investigate the catalytic performance of Ni/NaP1 and Ni/MSOD catalysts loaded with active components.The main contents are as follows:（1）The inorganic anion directing agent were screened during the synthesis of MSOD zeolite.The results showed that SO₄^2-ions have excellent characteristics and can induce the cubic morphology of A molecular sieve to transform from LTA to spherical MSOD zeolites.The prepared MSOD zeolites has the advantages of high purity and fast crystallization speed.The effects of crystallization temperature,crystallization time,and calcination temperature on the purity of MSOD synthesis are discussed.Experiments show that purity of MSOD zeolites can be obtained by calcination at 850℃and crystallization at 95℃for 10 h.The surface of the zeolites were acidic.There are mesopore-sized cracks formed during the crystal transformation process.The effects of preparation conditions,reduction conditions and reaction conditions on the catalytic performance of Ni/MSOD catalyst were investigated in the n-heptane catalytic isomerization reaction.The results showed that when the metal loading were 4 wt%,the calcination temperature were 400℃,and the calcination time were 4 h,The catalytic performance were better when the reduction temperature were 400℃,the reduction time were 4 h,the hydrogen flow rate were 30 ml/min,the reaction temperature were 300℃,and the reaction time were 5 h.The maximum yield were 34%,and the conversion rate to n-heptane The selectivities for and isoheptane are 56.56%and 60.38%,respectively.（2）NaP1 molecular sieve were prepared by using rice husk as silicon source under the condition of no template and non-high pressure.The optimal synthesis conditions of NaP1zeolite are explored through experiments,and the crystallinity of NaP1 crystals can be as high as 99.38%.The 4 wt%Ni/NaP1 catalyst has a calcination temperature of 400℃,a calcination time of 4 h,a reduction temperature of 400℃,a reduction time of 4 h,a hydrogen flow rate of 30 ml/min,a reaction temperature of 320℃,and reaction time of the catalytic performance more than 2 h were better,the maximum yield were 46%,the conversion to n-heptane and the selectivity to isoheptane are 65.49%and 70.86%,respectively.