Dry Reforming of Methane Using Ce-modified Ni Supported on 8%PO4 + ZrO2 Catalysts

Abstract

Dry reforming of methane (DRM) was studied in the light of Ni supported on 8%PO 4 + ZrO 2 catalysts. Cerium was used to modify the Ni active metal. Different percentage loadings of Ce (1%, 1.5%, 2%, 2.5%, 3%, and 5%) were tested. The wet incipient impregnation method was used for the preparation of all catalysts. The catalysts were activated at 700 • C for 1 2 h. The reactions were performed at 800 • C using a gas hourly space velocity of 28,000 mL (h·gcat) −1 . X-ray diffraction (XRD), N 2 physisorption, hydrogen temperature programmed reduction (H 2 -TPR), temperature programmed oxidation (TPO), temperature programmed desorption (TPD), and thermogravimetric analysis (TGA) were used for characterizing the catalysts. The TGA analysis depicted minor amounts of carbon deposition. The CO 2 -TPD results showed that Ce enhanced the basicity of the catalysts. The 3% Ce loading possessed the highest surface area, the largest pore volume, and the greatest pore diameter. All the promoted catalysts enhanced the conversions of CH 4 and CO 2 . Among the promoted catalysts tested, the 10Ni + 3%Ce/8%PO 4 + ZrO 2 catalyst system operated at 1 bar and at 800 • C gave the highest conversions of CH 4 (95%) and CO 2 (96%). The stability profile of Cerium-modified catalysts (10%Ni/8%PO 4 + ZrO 2 ) depicted steady CH 4 and CO 2 conversions during the 7.5 h time on stream.Catalysts 2020, 10, 242 2 of 16 the dry reforming of CH 4 . They tested the catalytic activity over La 0.4 M 0.6 Al 0.2 Ni 0.8 O 3 (M = Pt, Pd, Ru, Rh, Ir) perovskite-type oxides with a surface area of 3.26-4.14 m 2 /g. It was obtained that the La 0.4 Rh 0.6 Al 0.2 Ni 0.8 O 3 catalyst revealed the best catalytic performance due to its high surface area, surface oxygen concentration, and good low-temperature reducibility. El Hassan et al. [18] studied the influence of Rh (0.2 and 0.5 wt %) to the Co/SBA-15 catalyst in the catalytic performance of dry reforming of CH 4 . It was found that Rh favored Co stabilization in the mesopores and was reduced at a much lower temperature. The nature of coke was affected and less γ-carbon formed on the Rh-containing sample. However, because of the high prices and limited availability of noble metals, the research has also focused on transition metals such as Co, Ni, Ti, which are broadly used for this process because of their high activity [19]. However, these catalysts are prone to quick deactivation due to coke deposition. Within the catalysts, Ni depicted the greatest performance due to its strong ability to break C-C/C-H bonds and activate CH 4 [20]. AKri et al. [21] elaborated the dry reforming of CH 4 employing atomically dispersed Ni atoms, stabilized by interaction with Ce-doped hydroxyapatite. Their results evidenced that the catalyst was very active and that isolated Ni atoms were inherently coke resistant. Ce doping of hydroxyapatite brought strong metal-support interactions which stabilized Ni single atoms toward sintering and favored the selective activation of only the first C-H bond in CH 4 . Goula et al. [22] inves...

Hydrodeoxygenation of oleic acid for effective diesel-like hydrocarbon production using zeolite-based catalysts

“…Noted, it was discovered that adding Ni as a dopant boosts the efficiency of zeolite in HDO and cracking [20]. Although many researchers have focused on the modification of zeolite catalysts in HDO and cracking reactions by the addition of various active metals such as noble metals (Pt, Pd, Ru) [21][22][23] and transition metals (Ni, Co, Mo) [5,[24][25][26], nevertheless, to the best of our knowledge, less study has focused on a detailed comparison of the effectiveness of HDO activity over pure zeolite beta and HZSM5 catalysts. Due to aforementioned finding, therefore, this study will highlight on the impact of zeolite beta and HZSM5 on the behavior and hydrocarbon selectivity of the oleic acid (OA) HDO reaction towards the diesel fraction.…”

Ceria promoted phosphate‐zirconia supported Ni catalyst for hydrogen rich syngas production through dry reforming of methane

“…On adding phosphate, the charge transfer bands of ZrO 2 are demolished which indicates the perturbation of charge transfer due to the addition of phosphate in the support structure. The UV band of Phosphate‐ zirconia supported nickel catalyst (Ni/PZr) catalyst is found at 286 nm for charge transfer from O 2− to octahedral Ni +2 , about 423 nm for the d‐d transition from 3A 2 g(F) state to 3T 1 g(P) the state of Ni +2 in octahedral/distorted octahedral environment and about 730 nm shows the d‐d transition from 3A 2 g(F) state to 3T 1 g(F) state of the Ni +2 octahedral environment 46 . The Ce/PZr catalyst shows a UV band of about 280 nm for the transition of O 2− to Ce +3 /Ce +4.…”

“…Acido‐basic property of catalyst surface is a crucial factor to catalyze a reaction. Ibrahim et al found that ceria addition causes growth of basic site over the surface and at 3 wt% ceria, it has a moderate amount of weak acid site/surface hydroxyl 46 We have characterized catalyst sample with NH 3 ‐TPD to know the distribution of the acidic sites over the catalyst surface. With increasing ceria loading, the acidic character in the low‐temperature range/weak acidic character decreases, and at 10Ni3Ce/PZr catalyst, a moderate amount of weak basic sites are present.…”

“…Cyclic H 2 TPR‐CO 2 TPD‐H 2 TPR profile of the 10Ni/PZr and 10Ni3Ce/PZr catalyst are shown in Figure 9. Ibrahim et al found that phosphate‐zirconia supported nickel catalyst and ceria promoted phosphate‐zirconia supported nickel catalyst has a wide variety of basic surface due to surface hydroxyl, surface oxygen anion, and lattice oxygen anion 46 . However, when CO 2 ‐TPD is carried out after H 2 ‐TPR; all basic sites hydroxyl/oxygen anion are removed under the H 2 reduction stream.…”

“…The nickel and phosphate are the major catalytic active sites for CH 4 dissociated. This surface has well accessible basic sites for CO 2 adsorption 46 where CO 2 is adsorbed as physically adsorbed CO 2 and chemisorbed CO 2 species as carbonate and carboxylate. CH 4 dissociation into “C and H 2 ” at catalytic active sites as well as subsequent removal of carbon deposit by CO 2 (through oxidation) are major reaction routes for uninterrupted H 2 rich syngas production.…”