Research Of Efficient Iron-based Shift Catalyst

Because of its better thermal stability, higher mechanical strength, longer life, cheaper cost as well as a certain sulfur resistance, the iron chromium based catalyst was widely used in high temperature water gas shift reaction to produce hydrogen. However, these catalysts have some problems such as poor low-temperature activity, large bulk density, poor ability of resistant boiling water, and high active temperature, etc. when used in commercial plants. This study focuses on the synthesis of iron-based water gas shift catalyst in order to overcome these shortcomings and technological properties of the high-efficiency catalysts were also examined. In addition, characterization of the catalysts was carried out using XRD, N2 physical adsorption, TEM, H2-TPR and TG-DTG.The high temperature water gas shift catalysts in this paper were synthesized using an impregnation and co-precipitation method. The active ingredient of the catalyst was nitrate, which reduced the number of washing times during its preparation process as well as reduced the sulfur content of the catalyst and the precipitant was the weak base. The experimental results revealed that the weak base was more conducive to the formation of rod-like crystal and reducing the bulk density.The influence of amount and charging method of copper, reaction temperature, terminal pH, drying way, aging time and calcination temperature on catalytic performance was investigated. The optimum preparation conditions obtained from the micro fixed bed reactor evaluation results were: fractional precipitation with NaHCO3 as precipitating agent, reaction temperature: 75°C, terminal pH: 10, aging time: 120 min, 120°C drying 3h, calcination temperature: 300°C. Catalysts were characterized by X-ray diffraction, H2-TPR to investigate different copper content and impregnation methods. The precursor was also analyzed by TG-DTG. The results showed that copper ions could enter the iron oxide inverse spinal structure and interacted with the divalent iron ion, which reduce the catalyst’s reduction temperature and improve the low-temperature performance of the catalyst. Catalysts synthesized using fractional precipitation method possessed better dispersion of active component and higher catalytic activity. Hydroxides could not decompose incompletely, if the calcination temperature below 300℃.However, iron oxide crystal phase would undergo irreversible change which could impact the activity of the catalysts, if the calcination temperature higher than 400℃.The influences of process conditions on the optimal catalyst’s catalytic performance were investigated. Moreover, thermal stability and anti-boiling water capability. The catalyst showed better performance and anti-boiling water capability under the water-gas ratio of 0.8 and space velocity of 9000 h-1. were also investigated. The results showed that the optimal catalyst possessed good low-temperature activity, thermal stability and anti-boiling water capability.This study applied to the preparation and production of iron-based high temperature water gas shift catalyst and had certain significance for further optimization preparation and middle test.