Sol–gel preparation of NiO/ZrO2(x)–MgO(100−x) nanocatalyst used in CO2/O2 oxidative dehydrogenation of ethane to ethylene: influence of Mg/Zr ratio on catalytic performance

Abstract

A series of NiO/MgO-ZrO 2 mixed oxide catalysts were prepared using the sol-gel method in which the content of MgO and ZrO 2 was varied and the NiO amount was maintained around 5 wt%. The synthesized samples were characterized by XRD, FESEM, PSD, TEM, EDX dot-mapping, FTIR and the BET techniques and tested for the dehydrogenation of ethane in the presence of CO 2 with limited amount of O 2 . Irrespective of the various Mg/Zr ratios, the uniform dispersion of NiO as a common feature of all synthesized samples was evident from the XRD and EDX results. As indicated by XRD and FESEM analyses, a decrease in the size of nanocrystallites and particles and also an increase in the specific surface area were found when MgO phase is present in the sample. The catalytic evaluations revealed that the existence of basic MgO leads to more efficient performance of zirconia especially at higher temperatures. Hence, using both ZrO 2 and MgO increased the ethane conversion and the ethylene yield. This could be attributed to the effect of high reducibility and low surface acidity. It was observed that among the synthesized catalysts, NiO/ZrO 2(75) -MgO (25) was the most active catalyst with an ethane conversion of 66.35 %. However, NiO/ZrO 2(25) -MgO (75) exhibited the best catalytic performance in the oxidative dehydrogenation of ethane with an ethylene yield of 56.9 % at 650°C. The smaller particle and crystallite size, the narrower particle size distribution, uniform dispersion of the active species and higher surface area with efficient base-acid characteristics seem to be responsible for the superior performance of NiO/ZrO 2(25) -MgO (75) catalyst.Graphical Abstract CO 2 /O 2 oxidative dehydrogenation of ethane was investigated over a series of sol-gel synthesized Ni/ZrO 2 -MgO catalysts differing in Mg/Zr ratio. The presence of MgO alongside zirconia contributed to obtain better textural properties and satisfying ethylene yield. The variation of Mg/Zr ratio indicates that there is optimum MgO content in Ni/ZrO 2(25) -MgO (75) for the best catalytic activity. It is found that Ni/ZrO 2(25) -MgO (75) nanocatalyst, with weight ratio of MgO/ZrO 2 :3/1, effectively dehydrogenated ethane to ethylene in the presence of CO 2 /O 2 at 650°C, giving 56.9 % ethylene yield. This is due to higher surface area, smaller particles and narrow distribution of particle size.

Highly robust ZrO2-stabilized CaO nanoadsorbent prepared via a facile one-pot MWCNT-template method for CO2 capture under realistic calcium looping conditions

“…The textural modification of nano-size adsorbents has been broadly investigated to hamper the agglomeration of nanoparticles [29][30][31][32][33][34][35]. Extensive studies have indicated the higher enhancement in the CO2 adsorption capacity of modified CaO by using ZrO2 as the promoter compared to other metal oxides [36].…”

Porous Silica Coated Ceria as a Switch in Tandem Oxidative Dehydrogenation and Dry Reforming of Ethane with CO2

“…The challenge faced by scholars is predominantly the improvement of catalytic activity and life cycle, which is strongly determined by the dispersion of metal species and coke deposition during the reaction. Different types of supports have been investigated, including those of acidic nature (Al 2 O 3 , [6] ZSM‐5, [5c,7] ZrO 2 , [8] SAPO‐34 [9] ), the neutral mesoporous SiO 2 materials, such as Silicalite‐1, [10] MCM‐41, [11] SBA‐15, [12] TUD‐1, [5b] SiO 2 [5a,13] etc ., and the mixed metal oxides of ZrO 2 ‐CeO 2 , [6a] ZrO 2 ‐MgO [14] . In revealing the significance of the acid property, appropriate acid strength ensured the activation of C−H bonds to form alkeneand prevented them from cleaving.…”

Continuous Synthesis of Uniformly Dispersed Mesoporous SBA-15 Supported Silver Nanoparticles in a Coiled Flow Inverter Reactor

“…In the past few decades, various methods, such as precipitation ( Arshad et al, 2019 ; Rahdar et al, 2019 ), sol-gel ( Delir Kheyrollahi Nezhad et al, 2016 ) and high-temperature pyrolysis ( Chen et al, 2020 ), have been developed to synthesize supported nanocatalysts. These methods were developed mainly in a batch reactor, which may lead to polydispersity of nanoparticles and batch-to-batch irreproducibility ( Marre and Jensen, 2010 ).…”