Methane Transformation in Presence of Carbon Dioxide on Activated Carbon Supported Nickel–calcium Catalysts

Abstract

The objective of the present work was to study the catalytic reformation of methane in presence of carbon dioxide on activated carbon-supported nickel and calcium catalysts. Results are very promising ones because they suggests that it is possible to transform methane on these catalysts by using mild reaction conditions.

Changes on Texture and Crystalline Phase of Activated Carbon-Supported Ni-Ca Catalyst During Dry Methane Reforming

“…This is a deactivation of 90% and 70% relative to initial activities for Ni/AC and Ni-Ca/AC, respectively. In a previous work [10], we showed that catalytic activity of Ca/AC is negligible [10]. Therefore the present results suggest that calcium, in the form of CaO or CaCO 3 [10], would play a promoter role in the present bimetallic system, as has been earlier reported [3,6].…”

“…(2) that in comparison to the crude catalyst the binding energy of nickel in Ni-Ca/AC decreased about 2 eV (from 855.8 eV to 853.9 eV) after He pre-treatment. By contrast, we showed [10] that in absence of calcium, the binding energy of Ni +2 , for Ni/AC, only decreased in about 0.9eV after He pre-treatment. The role of electron donors of CaO and CaCO 3 is well-known [15] and the present result suggest that calcium phases would induce an easier reduction of Ni +2 to lower oxidation states, probably by its interaction with carbon atoms from support [8].…”

“…Ni(5wt%)-Ca(1wt%) catalyst was prepared by incipient wetness impregnation with nickel and calcium nitrate solutions on a commercial activated carbon (AC) purchased from Merck [Langmuir surface area 907m 2 g -1 , 22Å mean pore width, ash content <1wt%] following the procedure described in previous works [10,11]. Impregnation order is given by the sequence of elements, i.e., Ni followed by Ca.…”

“…Impregnation order is given by the sequence of elements, i.e., Ni followed by Ca. This catalyst was chosen because in a previous study [10] it showed the best activity for dry methane reforming. Characterization by N 2 adsorption-desorption isotherms, Xray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM, HR-TEM) was performed.…”

“…Activated carbon (AC) presents several advantages such as low cost, control of texture and surface chemistry during synthesis, high thermal conductivity, easy recovery of active phase from deactivated catalysts and so on [8,9] to be employed as catalytic support. However, activated carbon is not a common catalytic support for methane reforming reactions [10] because it can suffer gasification by steam or by CO 2 . Both reactions are spontaneous at about 700ºC but in a preliminary study of dry methane reforming on a carbon-supported Ni-Ca catalyst [11] we showed CO 2 can help control excess of carbon deposits without any detrimental effect on carbon supports after 5h reaction at 650ºC.…”