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• DME carbonylation is conducted in fluidized bed reactor to enhance the methyl acetate productivity. • Parametric studies on operating conditions were conducted for process optimization. • Optimized MA production can effectively bring economic and environmental benefits through the TEA and LCA. The carbonylation of bio-based dimethyl ether (DME) using ferrierite offers a renewable approach to methyl acetate (MA) production with a potential reduction in carbon emissions. This work showcases the feasibility of employing fluidized-bed reactors in this process, leveraging benefits such as effective solid mixing, uniform temperature distribution, and facile catalyst purge and makeup. Through parametric studies, the impact of operating conditions on the reaction kinetics and reactor hydrodynamics was elucidated. Both physical and chemical catalyst deactivation were found to be dependent on the fluidization regime. Numerical models based on experimental results enabled the prediction of reaction yield and selectivity in the process simulation and optimization. Preliminary techno-economic analysis (TEA) and life cycle assessment (LCA) showed the potential for a 40% reduction in production costs and an 8% reduction in the global warming potential compared to the fossil-based benchmark. Overall, this study highlights the operation simplicity, cost competitiveness, and environmental benefit of MA production from DME carbonylation in a fluidized-bed reactor, providing insights for process scale-up and feedstock sourcing. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon nitride protective layer successfully suppresses Ce ion dissolution from CeO 2. • Carbon nitride can mediate the hydroxyl radical scavenging reaction. • C 2 N coated CeO 2 prevents OCV and performance decay of MEA during OCV holding test. • Postmortem analysis substantiates C 2 N layer restrains catalyst degradation by Ce ion. A radical scavenger, CeO 2 , effectively improves the chemical durability of fuel cell membranes, however, Ce4+ ions eluted from the CeO 2 lead to Pt/C degradation and diminished power performance. To address the detrimental effect, we prepared a carbon nitride (C 2 N) coating on CeO 2 nanoparticles. The C 2 N protective layer reduced the Ce4+ dissolution rate 11-fold compared with pristine CeO 2. Density functional theory calculations suggest that the C 2 N structure suppresses Ce4+ dissolution by strongly binding the Ce4+. Furthermore, it has a profoundly lowered band gap in contact with CeO 2 , enabling C 2 N-mediated electron transfer for efficient radical scavenging reaction. A membrane electrode assembly fabricated using the C 2 N-coated CeO 2 exhibited excellent open circuit voltage durability for more than 600 h, without any loss in power performance. The judicious surface engineering of CeO 2 avoids the deep-rooted trade-off between membrane and catalyst layer durability. [ABSTRACT FROM AUTHOR]

Combined steam and carbon dioxide reforming with CH 4 (CSCR) has been investigated using Ni/Al 2 O 3 catalysts, where γ-Al 2 O 3 support was previously modified with four different organic acids before nickel impregnation, to verify the effects of different nickel distributions induced from the modified acid sites to the catalytic activity. The CSCR reactions were performed at T = 750 °C, P = 1.0 MPa, space velocity of 36,000 L(total mixed gas)/(kg cat ·h), and CH 4 /CO 2 /CO/H 2 /H 2 O molar ratio = 1/0.38/0.29/2.09/1.2, which is the typical compositions of the coke oven gas in steel industry. The Ni/Al 2 O 3 prepared by formic acid for the pretreatment of γ-Al 2 O 3 showed a higher catalytic activity due to the maintenance of smaller nickel particles even after a high temperature CSCR reaction. The types of organic acids significantly changed the surface properties of γ-Al 2 O 3 by varying the isoelectric points, which are strongly depending on pKa values of organic acids, and it concomitantly alters the dispersion of nickel precursor with the different deposition depths in γ-Al 2 O 3 pores by largely changing the particle size distribution and the metal-support interaction. The surface-enriched nickel containing Ni/Al 2 O 3 pretreated with oxalic acid was also applied to derive the kinetic parameters using Langmuir–Hinshelwood–Hougen–Watson (LHHW) mechanism by showing an activation energy of ∼240 kJ/mol for the CSCR reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The size of ionomer aggregate in dispersion is controllable with organic cosolvent. • The ionomer distribution and porosity of catalyst layers are designed. • Uniform ionomer distribution is preferred for cathode catalyst layer. • Water flooding can be mitigated by increasing the porosity of anode catalyst layer. The development of anion exchange membranes and ionomers plays a critical role in performance of anion exchange membrane fuel cells. However, the optimal design of catalyst layer structures still remains unexplored despite its significance. Herein, the rational design guide is presented for cathode and anode catalyst layers using m -TPN1 ionomer by controlling the size of ionomer aggregates in dispersion and comparing various catalyst layer structures. The size of m -TPN1 aggregates decreases, creating a more uniform ionomer distribution and a larger triple-phase-boundary. As ionomer distribution of the cathode catalyst layer becomes more uniform, the power density of membrane-electrode-assembly is enhanced. Also, the power density at fully humidified condition strongly correlates with the porosity of anode catalyst layer due to the limitation of hydrogen transport at anode by water flooding. [ABSTRACT FROM AUTHOR]

• Horse manure (HM) was employed as a feedstock for bioethanol production. • High holocellulose contents in HM produced fermentable sugars with 80% yield. • N-rich HM showed competitive ethanol production (0.075 g L-1h−1) with no N support. Insecure supply chain of biomass has been regarded as one of the critical constraints for deteriorating the practical implementations of bioethanol (BE). To find a raw feedstock beyond lignocellulosic biomass, horse manure (HM) was converted into BE. To realize the grand premise, two pretreatment methods, acid-/alkaline-pretreatments using H 2 SO 4 /NaOH, were used for HM. To optimize acid-/alkaline-pretreatments, the surface methodology response with the Box-Behnken design was done. Under the optimized conditions, alkaline-pretreatment showed higher maximum sugar recovery yield (80%) than that from acid- pretreatment (71%), which offers that alkaline-pretreatment is suitable for BE synthesis from HM. The fermentability of acid/enzyme- and alkaline/enzyme-hydrolysates without a supplement of nitrogen source were tested using GRAS strain of yeast, Pichia stipitis. The results indicated that alkaline/enzyme- hydrolysates showed higher BE productivities (0.075 g L-1h−1) than those of acid/enzyme-hydrolysates (0.050 g L-1h−1). To elucidate the possible reasons of such higher BE productivities from the alkaline/enzyme- hydrolysates, the potential fermentative inhibitory compounds for Pichia stipitis such as acetic acid, furfural, and hydroxymethylfurfural were quantitatively analyzed. The results indicated that the presence of less amounts of toxic compounds from the alkaline/enzyme- hydrolysates may lead to such higher BE productivities as compared those present in acid/enzyme-hydrolysates. Also, all experimental results suggested a potential for saving production cost of BE using HM as the C/N sources without an additional nitrogen source supplement. [ABSTRACT FROM AUTHOR]

• Micro-bubble is generated under pressurized condition in air-kerosene bubble column. • Formation of micro-bubble affects bubble characteristics. • Gas holdup of micro-bubble can be predicted by DGD method. Bubble characteristics of air-kerosene system and air-water system in a pressurized bubble column were analyzed. Experiments were carried out at system pressure up to 3.5 MPa on a cylindrical stainless column with an inner diameter of 0.097 m and a height of 1.8 m. Kerosene and tap water were used as liquids while air was used as gas. Bubble characteristics were observed by varying gas velocity up to 98 × 10−3 m/s at 0.1 MPa and up to 31.1 × 10−3 m/s at 3.5 MPa. Bubble chord length and bubble rising velocity were measured with a single tip probe installed at the top of the distributor at 0.5 m. In addition, pressure difference between the top and bottom of the column was measured with a differential pressure transducer to confirm gas holdup. In the air-kerosene system, gas holdup tended to increase with increasing system pressure. From the analysis of drift flux, transition from homogeneous to heterogeneous flow regime was observed only under atmospheric pressure. In the air-kerosene system, drift flux tended to be kept constant as gas holdup increased under pressurized conditions. The system pressure was varied from 0.1 MPa to 3.5 MPa to confirm micro-bubble generation under pressurized conditions. Dynamic gas disengagement (DGD) analysis and image analysis at the same time showed that gas holdup fraction of micro-bubbles was almost constant (ε m /ε g = 0.4) at atmospheric pressure. However, it was increased from 0.48 at gas velocity of 12.3 × 10−3 m/s to 0.57 with gas velocity of 32.1 × 10−3 m/s at 3.5 MPa. [ABSTRACT FROM AUTHOR]