Study On Preparation Of Modified Palygorskite Catalyst And Catalytic Cracking Of Xylene As Model Compound Of Biomass

As an increasing development and wide application of the technology of biomass pyrolysis and gasification, the impact of biomass pyrolysis tar is paid more and more attention. In this paper, based on the previous research on the nature and structure of palygorskite(PG), xylene catalytic cracking (steam reforming) reaction is carried out in-depth experimental study taking palygorskite as catalyst and xylene as model compound of biomass.On the analysis of the previous research on this topic, a gas-solid reactor for catalytic cracking is established in laboratory-scale, and gas chromatography is used to analyze the composition and content of the gases produced in catalytic cracking reaction. Volume impregnation method is implemented in the active component (NiO) load of the purified palygorskite. The loaded palygorskite is dried and calcined to get Ni/PG catalyst with different amount of Ni-supported. XRD, TEM, BET and other means are used to detect and characterize the structural characteristics and properties of the catalyst. Through the evaluation of the activity of the catalyst, the major preparation parameters (Ni loading, calcination temperature, etc.) and operating conditions (reaction temperature, space velocity, water vapor content) are optimized and the main factors of the rate of xylene are also analyzed. The rule of catalyst activity with the changes of reaction time is reviewed, and it is concluded that the possible cause of catalyst deactivation generally is carbon deposition and the damage of catalyst surface structure. Through the online analysis on cracked gas components, the selective factor of catalyst is researched. It is attempted to put forward the mechanism of steam reforming reaction processing xylene and palygorskite loaded Ni. It is not only observed that the presence of water vapor is an effective factor to eliminate carbon deposition of catalyst, but also found that the activity of catalyst is dependent on the structure of palygorskite. In conclusion, this paper shows that the palygorskite loaded Ni is an good catalyst to remove biomass gasification tar mainly composed of aromatics. This paper also provide technical parameters and theoretical support for the industrialization of catalytic technology in the conversion of tar.