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• Higher diffusion rate was observed in hollow ZSM-5 with large cavities • Mass transfer was restricted by micropores and surface barriers over hollow ZSM-5 • The stability of hollow ZSM-5 was lower than that of mesoporous ZSM-5 in MTA Comparing the effects of hollow and mesoporous structures over ZSM-5 zeolites on catalytic behaviors in methanol aromatization was done. Hollow zeolites possessing larger voids, increasing Bronsted acid sites and more framework Al in channel crossings promoted higher benzene, toluene and xylene (BTX) selectivity. Zero-length column (ZLC) desorption of cyclohexane stated that higher diffusion rate was observed over mesopores zeolite and hollow zeolite. However, lower effective diffusion constants (D eff) and higher activation energy of hollow zeolite demonstrated that mass transfer was not only limited by microporosity but by surface barriers resulting from surface defects and pore blockage. The highest diffusion rate of cyclohexane over hollow zeolite was presented indicating that surface barrier was not dominant in diffusion limitation. The stability of hollow ZSM-5 was lower compared to mesoporous ZSM-5 as a result of more strong acid sites and higher external silanol groups, which favored to carbon deposition. Additionally, the collapse of hollow structures with thinner shells also contributed to higher deactivation rate. [Display omitted] [ABSTRACT FROM AUTHOR]

• The acid distribution in HMOR zeolite can be oriented-tailored. • The amount of B 8-MR in HM-PN-2 is twice as much as the HM sample. • The reactivity of DME carbonylation can be largely enhanced over HM-PN-2. • Outstanding stability can be further realized over pyridine modified HMOR. Directional adjusting of the distribution of Brønsted acid site (BAS) in zeolite to control its catalytic performance is highly attractive but remains challenging. This study aims to tailor the distribution of BAS in 8-membered ring (B 8-MR) of H-Mordenite (HMOR) by adding aniline or p -phenylenediamine as additives to the sol‐gel. The results reveal that the number of B 8-MR is significantly increased but with a slight change in the number of BAS in 12-membered ring channels. When using dimethyl ether (DME) carbonylation as the probe reaction, the conversion of DME to methyl acetate over the synthesized HMOR zeolite is increased by nearly 2 times. Our finding not only provides a facile strategy to regulate the acid distribution in different channels of the HMOR zeolite but also offers a promising candidate for the catalytic DME carbonylation, which is a critical intermediate step for ethanol synthesis from syngas. [ABSTRACT FROM AUTHOR]

High-performance supercapacitors extremely depend on reasonable microstructure of electrode materials, but how to efficiently control the pore structure of principal carbon materials remains a challenge. In this study, corncob-based porous carbon (CPC X) with controllable pore structures is synthesized by means of KOH activation strategy, and the technical parameters of KOH activation are comprehensively investigated including activation temperature, activation time and KOH/biochar ratio. The optimal sample with a KOH/biochar mass ratio of 3 activated at 650 °C for 1 h (denoted as CPC 650 – 1-3) possesses sub-nanopores concentrated at 0.6 nm and 0.8 nm, and larger micropores distribute at 1.2 nm and 1.5 nm. These highly cross-linked microporous structures provide accessible specific surface area (SSA) for electrode materials and act as high-speed channels for fast ion diffusion and transfer. The activated carbon material has a high SSA (2998 m2 g−1) and a large V micro /V meso ratio of 8.26. The specific capacitance of CPC 650 – 1-3 reaches 258 F g−1 at 0.5 A g−1 and remains a satisfied retention of 74 % even at 10 A g−1. Moreover, CPC 650 – 1-3 //CPC 650 – 1-3 symmetric supercapacitors exhibit a high energy density of 6.4 Wh kg−1 at power density of 500.1 W kg−1. It also has a capacitance retention of 90.1 % after 10,000 cycles, highlighting its excellent cycle stability. These results indicate that corncob-based microporous carbon materials have broad application prospects in promoting the high added-value utilization of biomass waste and the development of high-performance supercapacitors. [Display omitted] • Microporous carbons were prepared from agricultural waste corncob. • The pore structure of materials was regulated by changing the activation conditions. • The relationships among activation conditions, V micro /V meso , specific surface area and specific capacitance were investigated. • A remarkable capacitance retention of 90.1 % after 10,000 cycles at 10 A g−1. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-doped MOR zeolites were synthesized using oxalic acid as the complexing reagent. • Fe atoms preferentially form Fe(OH)Si groups at the 8-MR rather than at the 12-MR. • Fe-doped MOR embrace gradient concentration of B 8‑MR and well-maintained B 12-MR. • The decreasing B 8-MR grants Fe-doped MOR good stability and high MA selectivity. Dimethyl ether (DME) carbonylation to methyl acetate (MA) paves a desirable way for producing ethanol from syngas. However, designing highly durable catalysts for it is still extremely challenging. In the work, we designed a series of Fe-doped MOR zeolites using oxalic acid as the complexing reagent by a template-free method. It is found that the complexed iron (III) preferentially locates at the T3 position of the eight-membered ring (8-MR). Over these Fe-doped MOR zeolites, the stability of DME carbonylation can be significantly enhanced. Contradictory to the conventional understanding of B 8-MR , we suggest that the decrease in the B 8-MR leads to relatively good stability, long introduce period, high MA selectivity and high MA production efficiency of B 8-MR. The work not only provides a new strategy for regulating the acid distribution of HMOR, but also offers a new understanding in the role of the B 8-MR in the carbonylation of DME. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spatial confinement in straight and sinusoidal channels strengths Brønsted acid sites in ZSM-5 zeolites. • Proximity and interaction between Brønsted acid sites enhance their strengths. • Stronger Brønsted acid sites hinder butenes oligomerization reactions. • Al sites at channel intersections with lower confinement favors butenes oligomerization and aromatization reactions. The relationship between Brønsted acid sites and framework Al distribution in the 10-membered ring (10-MR) straight and sinusoidal channels and their channel intersections in ZSM-5 zeolites were investigated using a range of analytical techniques. Spatial confinement in the straight and sinusoidal channels not only strengthens interactions between Brønsted acid sites and guest molecules, but also promotes proximity and interaction between Brønsted acid sites with the same chemical shift, enhancing their strengths. Stronger Brønsted acid sites do not benefit the conversion of butenes in oligomerization reactions owing to restriction of their migration and diffusion. However, the Al sites at channel intersections are more spacious, and the lower confinement therein favors selectivity for butene oligomerization products (C8) and n -butene aromatization products (BTX and C9 + aromatics). [ABSTRACT FROM AUTHOR]

Abstract: Photocatalytic depolymerization (PCDP) of rice husk (RH) over TiO2 in H2O2 aqueous solution under ultraviolet irradiation was investigated. The reaction mixture was fractionated into different extracts by filtration and subsequent sequential extraction with different organic solvents. In total, 172 organic compounds were identified in the extracts with GC/MS. The compounds can be classified into alkanes, alkenes, arenes, non-substituted alkanols, substituted alkanols, alkenols, phenols, alkanals, alkenals, benzaldehydes, ketones, carboxylic acids, alkanoates, phthalates, nitrogen-containing organic compounds, sulfur-containing organic compounds and other species. Alkanes are the most abundant in the group components. They resulted from the degradation of waxes in RH. Aldehydes and ketones were also detected with high relative contents, most of which were derived from cellulose, hemicellulose and waxes. Phthalates and arenes resulted from lignin degradation. Lignin–wax and hemicellulose–wax interlinkages are proposed to be new structures. According to the species identified in the extracts, the mechanisms for photocatalytic oxidation of benzene ring-containing compounds are proposed. The PCDP of RH provides an alternative way to obtain value-added chemicals from biomass with low energy consumption and under eco-friendly conditions. [Copyright &y& Elsevier]

[Display omitted] • The Ni@Fe/NC shows good activity and selectivity for cleaving C-O bond in lignin. • NiFe alloy is formed in the catalyst which plays a crucial role in hydrogenolysis. • Aromatics especially guaiacols are dominant products from hydrogenolysis of lignin. • Possible reaction pathways based on hydrogenolysis of BPE and lignin were proposed. The utilization of lignin to produce high value-added chemicals is conducive to alleviating the fossil energy crisis. Herein, Ni nanoparticles supported on iron/nitrogen co-doped carbon was prepared by co-pyrolysis and solvothermal reduction method for catalytic hydrogenolysis (CH) of dealkaline lignin and its model compounds. The catalysts were prepared under different calcination temperature, N/C ratio and Ni loading, and the optimal catalyst was Ni 10% @Fe/NC 0.33 – 800 (calcination temperature: 800 °C, N/C ratio: 0.33, Ni loading: 10%) based the on the CH of benzyl phenyl ether (BPE). Ni 10% @Fe/NC 0.33 – 800 showed good catalytic performance on the selective cleavage of C-O bond of lignin and its model compounds. The BPE conversion reached up to 97.7% over Ni 10% @Fe/NC 0.33 – 800 under mild conditions (230 °C, 1 MPa H 2 , and 0.5 h) with toluene and cyclohexanol as major products. Catalyst characterizations suggest that N content affects the formation of NiFe alloy and the synergistic effect between Ni and Fe plays an important role in CH of BPE. Moreover, Ni 10% @Fe/NC 0.33 – 800 could promote the cleavage of C-O bonds in dealkaline lignin through CH and hence enhance producing aromatics such as phenols, aromatic ethers, and aromatic esters, among which phenols are the main aromatics with guaiacols predominant. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass has gained growing interest as a promising substitute for the production of renewable and sustainable chemicals and fuels as the dwindling fossil-fuel reserves. Pyrolysis without using any chemical reagent is an effective method to depolymerize cellulose into kinds of value-added chemicals. Herein, we summarized recent progress about non-catalytic and catalytic pyrolysis of cellulose into specific chemicals, including levoglucosan, 1-hydroxy-3,6-dioxabicyclo[3.2.1]octan-2-one, levoglucosenone, furans, aromatics, and olefins via dehydration, aromatization, and aldol condensation, etc. An analysis and summary of the optimal conditions of these value-added chemicals by catalytic pyrolysis of cellulose are benefit to develop better production methods. In addition, the potential challenges and future perspectives for the pyrolysis of cellulose to chemicals are also discussed to provide a feasible direction for relevant researchers to advance industrialization. [Display omitted] • Pyrolysis of cellulose to specific value-added chemicals is systemically reviewed. • The formation mechanisms of cellulose-derived chemicals are summarized. • An analysis and summary of previous results are benefit to improve the product productions. • Future directions and perspectives for pyrolysis of cellulose to chemicals are outlined. [ABSTRACT FROM AUTHOR]