Catalytic co-pyrolysis of oil palm trunk and polypropylene with Ni–Mo/TiO2 and Ni/Al2O3: Oil composition and mechanism

Pyrolysis oil from oil palm biomass can be a sustainable alternative to fossil fuels and the precursor for synthesizing petrochemical products due to its carbon-neutral properties and low sulfur and nitrogen content. This work investigated the effect of applying mesoporous acidic catalysts, Ni–Mo/TiO2 and Ni/Al2O3, in a catalytic co-pyrolysis of oil palm trunk (OPT) and polypropylene (PP) from 500 to 700 °C. The obtained oil yields varied between 12.67 and 19.50 wt.% and 12.33–17.17 wt.% for Ni–Mo/TiO2 and Ni/Al2O3, respectively. The hydrocarbon content in oil significantly increased up to 54.07–58.18% and 37.28–68.77% after adding Ni–Mo/TiO2 and Ni/Al2O3, respectively. The phenolic compounds content was substantially reduced to 8.46–20.16% for Ni–Mo/TiO2 and 2.93–14.56% for Ni/Al2O3. Minor reduction in oxygenated compounds was noticed from catalytic co-pyrolysis, though the parametric effects of temperature and catalyst type remain unclear. The enhanced deoxygenation and cracking of phenolic and oxygenated compounds and the PP decomposition resulted in increased hydrocarbon production in oil during catalytic co-pyrolysis. Catalyst addition also promoted the isomerization and oligomerization reactions, enhancing the formation of cyclic relative to aliphatic hydrocarbon

Bifunctional hydrous RuO2 nanocluster electrocatalyst embedded in carbon matrix for efficient and durable operation of rechargeable zinc-air batteries

Ruthenium oxide (RuO2) is the best oxygen evolution reaction (OER) electrocatalyst. Herein, we demonstrated that RuO2 can be also efficiently used as an oxygen reduction reaction (ORR) electrocatalyst, thereby serving as a bifunctional material for rechargeable Zn-air batteries. We found two forms of RuO2 (i.e. hydrous and anhydrous, respectively h-RuO2 and ah-RuO2) to show different ORR and OER electrocatalytic characteristics. Thus, h-RuO2 required large ORR overpotentials, although it completed the ORR via a 4e process. In contrast, h-RuO2 triggered the OER at lower overpotentials at the expense of showing very unstable electrocatalytic activity. To capitalize on the advantages of h-RuO2 while improving its drawbacks, we designed a unique structure (RuO2@C) where h-RuO2 nanoparticles were embedded in a carbon matrix. A double hydrophilic block copolymer-templated ruthenium precursor was transformed into RuO2 nanoparticles upon formation of the carbon matrix via annealing. The carbon matrix allowed overcoming the limitations of h-RuO2 by improving its poor conductivity and protecting the catalyst from dissolution during OER. The bifunctional RuO2@C catalyst demonstrated a very low potential gap (triangle EOER-ORR=ca. 1.0V) at 20 mA cm(-2). The Zn|| RuO2@C cell showed an excellent stability (i.e. no overpotential was observed after more than 40 h)

Enhanced hydrogen production from thermochemical processes

To alleviate the pressing problem of greenhouse gas emissions, the development and deployment of sustainable energy technologies is necessary. One potentially viable approach for replacing fossil fuels is the development of a H2 economy. Not only can H2 be used to produce heat and electricity, it is also utilised in ammonia synthesis and hydrocracking. H2 is traditionally generated from thermochemical processes such as steam reforming of hydrocarbons and the water-gas-shift (WGS) reaction. However, these processes suffer from low H2 yields owing to their reversible nature. Removing H2 with membranes and/or extracting CO2 with solid sorbents in situ can overcome these issues by shifting the component equilibrium towards enhanced H2 production via Le Chatelier's principle. This can potentially result in reduced energy consumption, smaller reactor sizes and, therefore, lower capital costs. In light of this, a significant amount of work has been conducted over the past few decades to refine these processes through the development of novel materials and complex models. Here, we critically review the most recent developments in these studies, identify possible research gaps, and offer recommendations for future research

Designing CO<inf>2</inf>-resistant oxygen-selective mixed ionic-electronic conducting membranes: Guidelines, recent advances, and forward directions

© 2017 The Royal Society of Chemistry. CO 2 resistance is an enabling property for the wide-scale implementation of oxygen-selective mixed ionic-electronic conducting (MIEC) membranes in clean energy technologies, i.e., oxyfuel combustion, clean coal energy delivery, and catalytic membrane reactors for greener chemical synthesis. The significant rise in the number of studies over the past decade and the major progress in CO 2 -resistant MIEC materials warrant systematic guidelines on this topic. To this end, this review features the pertaining aspects in addition to the recent status and advances of the two most promising membrane materials, perovskite and fluorite-based dual-phase materials. We explain how to quantify and design CO 2 resistant membranes using the Lewis acid-base reaction concept and thermodynamics perspective and highlight the relevant characterization techniques. For perovskite materials, a trade-off generally exists between CO 2 resistance and O 2 permeability. Fluorite materials, despite their inherent CO 2 resistance, typically have low O 2 permeability but this can be improved via different approaches including thin film technology and the recently developed minimum internal electronic short-circuit second phase and external electronic short-circuit decoration. We then elaborate the two main future directions that are centralized around the development of new oxide compositions capable of featuring simultaneously high CO 2 resistance and O 2 permeability and the exploitation of phase reactions to create a new conductive phase along the grain boundaries of dual-phase materials. The final part of the review discusses various complimentary characterization techniques and the relevant studies that can provide insights into the degradation mechanism of oxide-based materials upon exposure to CO 2

High temperature oxygen separation using dense ceramic membranes

© Springer Science+Business Media, LLC 2012 and Springer International Publishing Switzerland 2017. Mixed ionic-electronic conducting (MIEC) ceramic membrane has rapidly become an attractive alternative technology to conventional cryogenic distillation for oxygen separation from air. Given the heat integration opportunity in most energy generation processes, this technology offers lower cost and energy penalty due to its capability to produce pure oxygen at high temperature ( &gt; 800°C). Using pure oxygen for combustion in turn facilitates the production of concentrated carbon dioxide gas downstream which can be easily captured and handled to mitigate the greenhouse gas effect. This chapter overviews and discusses all essential aspects to understand oxygen selective MIEC ceramic technology. The basics behind the formation of defects responsible for high-temperature ionic transport are explained together with the transport theory. Two major family structures, e.g., fluorite and perovskite, which become the building blocks of most MIEC materials are discussed. Specific structure and properties as well as the advantages and the drawbacks of each family are explained. Some important structural considerations, e.g., crystal structure packing and Goldschmidt tolerance factor, are elaborated due to its strong relationship with the properties. Two additional concepts, e.g., dual-phase membrane and external short circuit, are given to address the drawbacks associated with fluorite and perovskite MIEC materials. Various geometries and types of MIEC membranes can be prepared, e.g., disk, tube, hollow fiber, or flat plate, each of which fits particular application. A short paragraph is presented at the end of the chapter on another possible application of this technology to facilitate a particular reaction to synthesize value-added products