چكيده به لاتين
With the increase in energy demand, the use of fossil fuels as primary sources of energy also increased due to their low costs and high heating value. The result of high energy consumption is the excessive production of carbon dioxide and global warming. The reforming reaction with methane steam is one of the most important and widely used reactions for the production of clean hydrogen fuel. Among the catalysts used in this reaction, nickel-based catalysts based on Al2O3, MgO, ZrO2 and mixed bases have received much attention. In this research, CaO: Al2O3 base with different percentages (10, 20, 30, 40, 50) was synthesized separately from the catalyst and combined by mechanical-chemical method. Then, the effect of different loadings of nickel (5, 7.5, 10, 12.5 and 15% by weight) on the base with optimal percentage of aluminum oxide and calcium oxide was investigated. According to the BET results, adding Al2O3 to CaO increased the specific surface area from 15 m2.g-1 to 52 m2.g-1. Also, with the increase of nickel oxide from 5 to 15% by weight, the specific surface area of the catalysts decreased. In addition, by increasing the molar percentage of CaO/Al2O3 from 0%: 100% to 55%: 45% and nickel from 5% to 10% by weight, the performance of the catalysts increased, which could be due to the good adsorption of carbon dioxide and improvement in the reversibility of the catalysts. be On the other hand, adding more CaO and nickel oxide decreased carbon dioxide absorption. Therefore, the 10wt.% NiO/Al2O3-45%CaO catalyst had the highest methane conversion and simultaneous absorption of carbon dioxide in the reforming reaction with methane steam at a temperature of 500°C to 700°C. Also, the effect of GHSV on the performance of the selected catalyst was evaluated and the results showed that the decrease in GHSV value from 24000 ml.grcat-1.h-1 to 12000 ml.grcat-1.h-1 increases the performance of the sample. to be In addition, with increasing feed ratio (H2O/CH4) from 1 to 5 at 500°C to 700°C, methane conversion increased. As a result, the 10wt.% NiO/Al2O3-45%CaO catalyst had the best performance with 96% methane conversion and 11% carbon dioxide production at 650 °C. Also, operating conditions including calcination temperature, reduction temperature, GHSV, feed ratio and long-term stability test were also investigated on the selected catalyst
