Asymmetric Tubular Oxygen-Permeable Ceramic Membrane Reactor for Partial Oxidation of Methane

Abstract

We report a successful paradigm of implementing the nickel catalyst for partial oxidation of methane (POM) in an oxygen-permeable ceramic membrane reactor (OPCMR). With using air feed, the OPCM (or the cathode of O 2 reaction) was completely gastight but presented a desirable oxygen anion flux, which is required by POM in the anodic side. An almost 100% of CH 4 conversion with high selectivity of CO and H 2 was achieved in the anode, which was initially a composite of YSZ and NiO. It is also found that a mutual diffusion of Ni 2+ and Zr 4+ ions happens between the YSZ and NiO phases, which affected performance of POM. Besides experimental work, a new activation pathway was proposed to describe cleavage of the first C-H bond of methane. This activation pathway was simulated using the density function-theory and the computed activation energy for breaking up the first C-H bond falls in the experimental measurement range.

Fabrication of a Metal Membrane on a Perforated Polymer Substrate by Palladium Aerosol Activation and Subsequent Electroless Plating

“…The results indicated an increase in the plating rate until 20 min plating, which is a characteristic of an autocatalytic reaction (19,38). The plating rate decreased after prolonged ELP (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) …”

Oxygen Transport Membranes and their Role in CO2 Capture and Syngas Production

“…Converting water and carbon dioxide into energy intensive commodities by solar powered unnatural photosynthesis has become more attractive in past few decades, by virtue of its significant part in extenuation of energy deficiency and global warming [12][13][14][15][16][17]. Syngas can be produced from splitting of H 2 O and CO 2 by means of solar thermochemical loop [18], having fast reaction kinetics and operating at higher temperature using the solar spectrum for thermal energy.…”

“…Common membrane designs comprise of asymmetric structures where thin, nonporous membranes are supported on a porous substrate providing the desired mechanical strength to the membrane. The porous substrate may be constructed from the same material as of membrane and apparently asymmetric membranes with thin nonporous layer and a porous support ( Figure 10) could defeat these problems [14]. In most of the cases, porous support having a pore size lesser than skin layer thickness is preferred instead of the one having adequate mechanical strength.…”

Reações de reforma de biogás sobre catalisadores de NiO-MgO-ZrO2 e NiO-Y2O3-ZrO2

“…Temperatura ( específica mostram uma diminuição da área superficial conforme o teor ítrio foi aumentando (a amostra com 4% ítrio apresentou o maior valor de área superficial); isto pode ser devido a que altos teores de ítrio favoreceram a formação de cristais de ZrO 2 de menor tamanho (9,8nm para Ni40YZ, Tabela 9); assim os pequenos cristais de ZrO 2 poderiam estar obstruindo os poros da superfície do catalisador, levando à baixos valores de área superficial. (raio iônico Y 3+ 0.93Å) na rede cristalina do NiO (raio iônico Ni 2+ = 0,78 Å), causando assim a expansão do parâmetro de rede do NiO (Tabela 9) devido à formação da solução sólida NiO-Y 2 O 3 (YIN et al, 2007;WANG et al, 2008). A formação da solução sólida nesse caso é possível devido a ambos os óxidos (NiO e Y 2 O 3 ) possuírem estrutura do tipo cúbica de face centrada (FCC) e raios iônicos adequados (WANG et al, 2008).…”

“…Figura 10 -DRX dos catalisadores NiO-Y 2 O 3 -ZrO 2 (antes da reação): (a) superposição dos difratogramas, (b) ampliação entre ângulos de Bragg de 62º a 64º, (c) ampliação entre ângulos de Bragg de 27º a 33º, (d) ampliação entre ângulos de Bragg de 40º a 48º dos catalisadores reduzidos em H 2 a 800 ºC (T: fase tetragonal da ZrO 2 , M: fase monoclínica da ZrO 2 ; NiO, Niº). Essa expansão do parâmetro de rede pode ser visualizada pelo deslocamento contínuo do pico principal (111) da fase tetragonal do ZrO 2 para menores ângulos de Bragg, conforme apresentado na Figura 10c (YIN et al, 2007;WANG et al, 2008). Nota-se também que o pico atribuído à fase tetragonal do ZrO 2 (Fig.…”