Investigation on Reverse Water–gas Shift over La2NiO4 Catalyst by Cw-cavity Enhanced Absorption Spectroscopy During CH4/CO2 Reforming

Abstract

Reverse water-gas shift (RWGS) reaction over La 2 NiO 4 catalyst was investigated during CH 4 /CO 2 reforming by continuous wave cavity enhanced absorption spectroscopy, a sensitive absorption technique. The results indicated that the RWGS reaction promoted the conversion of CO 2 and decreased the partial pressure of hydrogen. By proper adjustment of the pressure of the reaction system, it is possible to suppress the occurrence of RWGS reaction and increase the selectivity of CH 4 /CO 2 reforming. The intermediates of CH 4 /CO 2 reforming such as CHO, OH and CH 3 were observed by means of the liquid-N 2 quenching technique, and a reaction step: CH x +[O]=CH x O was primarily confirmed. In addition, XPS and XRD results verified that nickel over catalyst after CH 4 /CO 2 reforming existed in elemental state. The HRTEM images of used catalyst indicated that the deactivation of catalyst was originated mainly from the formation of nanotubes and graphite carbon on active sites of nickel.

Preparation and High Performance of La2O3−V2O5/MCM-41 Catalysts for Ethylbenzene Dehydrogenation in the Presence of CO2

“…The results of CO 2 -TPD analysis verified that the introduction of La 2 O 3 results in the retention of CO 2 in the 500-600°C range due to the formation of La 2 O 2 CO 3 . 27 The adsorption and desorption of CO 2 in the 350-650°C range is catalytically more relevant because the EBDH reaction occurs in the 500-600°C range. Figure 6 showed the NH 3 -TPD spectra of different samples.…”

Performance of 3%Mo/ZSM-5 catalyst in the presence of water during methane aromatization in supersonic jet expansion

“…Under the SJE condition, we do not detect C 2 H 4 þ , C 2 H 6 þ , and C 6 H 6 þ but CHO þ in a span of 165 min (Figure 2c). The identity of CHO þ was confirmed before through the detection of 13 CHO þ when 13 CH 4 (rather than 12 CH 4 ) was introduced to the reactor under SJE condition. 17 As suggested, CHO is formed as a result of CH x interaction with oxygen on the surface of 3%Mo/HZSM-5, and the decomposition of HCO gives CO and H. 12 Apparently, it is hard to detect the CHO intermediates under normal condition.…”

“…12,13 With rapid departure of hydrogen and aromatics from catalyst, product/catalyst interaction is limited and coke formation is not serious. In CH 4 /CO 2 reforming reactions over La 2 NiO 4 and 10%NiO/ CeO 2 -La 2 O 3 catalysts, we found that CO 2 and CH 4 conversions under SJE condition were significantly higher than those at equilibrium.…”

“…Later, we reported that under supersonic jet expansion (SJE) condition, the MDA reaction (6CH 4 ¼ C 6 H 6 þ 9H 2 ; 10CH 4 ¼ C 10 H 8 þ16H 2 ) is over within a short time ($10 À3 s) before reaching reaction equilibrium. 12,13 With rapid departure of hydrogen and aromatics from catalyst, product/catalyst interaction is limited and coke formation is not serious. In CH 4 /CO 2 reforming reactions over La 2 NiO 4 and 10%NiO/ CeO 2 -La 2 O 3 catalysts, we found that CO 2 and CH 4 conversions under SJE condition were significantly higher than those at equilibrium.…”

Temperature-programmed Studies of Coke Resistant Ni Catalyst for Carbon Dioxide Reforming of Methane

“…Carbon dioxide (CO 2 ) reforming of methane to synthesis gas attracts ever-growing interest from both environmental and industry aspects [1][2][3][4][5][6]. It provides a practical and effective way for the utilization of the two major greenhouse gases (CO 2 and methane) [2].…”