مهتاب كريمي

Global warming with the increasing greenhouse gases such as carbon dioxide increases the need to reduce greenhouse gases and also to use green energy sources. Dry reforming of methane by converting two greenhouse gases methane and carbon dioxide and also producing hydrogen is considered a potential process for the aforementioned purposes. Also, the ratio of hydrogen to carbon monoxide produced as the main products of dry reforming of methane, known as synthesis gas, is important in many industries. Synthesis gas with a ratio of one is used as a feed for some chemical processes. In the dry reforming of methane, the formation of carbon on the surface of the catalyst is known to be an obstacle to the application of this process on an industrial scale. Various catalysts were studied with the aim of improving the anti-carbon properties and stability of the catalyst. In this research, nickel catalyst based on alumina was used as the base catalyst and some rare earth elements were used as catalyst promoters. Initially, by examining the amounts of 10, 15 and 20% nickel on alumina, the 15% nickel catalyst showed the lowest carbon content and stability and a methane conversion percentage of 76.25 at 700°C and was considered as the baseline. Subsequently, 3% of rare earth promoters (yttrium, cerium and lanthanum oxides) were inoculated onto the catalyst and the catalyst promoted with lanthanum oxide showed the lowest carbon content and a conversion percentage of 82.42 among the promoted catalysts. Lanthanum oxide also improved the dispersion of nickel and therefore the lanthanum oxide promoter was considered as the preferred promoter. Subsequently, 1 and 5% of the lanthanum oxide promoter were synthesized on the catalyst and it was observed that by adding 5% lanthanum oxide to the catalyst, the methane conversion percentage decreased to 74.42 due to the occupation of the catalyst surface; however, the catalyst promoted with 3% and then 1% lanthanum oxide promoted the methane conversion percentage to 84.42 and 78.2%. The catalyst promoted with 3% lanthanum oxide was considered as the desired catalyst by showing a methane conversion percentage of 84.42 and the formation of carbons that did not significantly affect the catalyst performance and was eva‎luated in order to determine the best reaction conditions under operating conditions of different gas space velocities and different feed ratios. The catalyst upgraded with 3% lanthanum oxide at a space velocity of 12000.ml.g_cat^(-1).h^(-1) showed a methane conversion of 82.94%, and feed ratios of 3, 2, and 1.5 showed methane conversions of 94.8, 94.09, and 87.84%.

گاز سنتز , عناصر خاكي كمياب , ريفرمينگ خشك متان , نيكل , گازهاي گلخانه‌اي

Synthesis gas , rare earth elements , dry methane reforming , nickel , greenhouse gases

Mahtab Karimi

S. Mehdi Alavi