Wiley

The present study describes an interesting and practical catalytic system that allows flexible conversion of lignin into aromatic or aliphatic hydrocarbons, depending on the hydrogen partial pressure. A combination of experiment and theory shows that the product distribution between aromatics and aliphatics can be simply tuned by controlling the availability of hydrogen on the catalyst surface. Noticeably, these pathways lead to almost complete oxygen removal from lignin biomass, yielding high‐quality hydrocarbons. Thus, hydrogen–lignin co‐refining by using this catalytic system provides high flexibility in hydrogen storage/consumption towards meeting different regional and temporal demands.

A three‐dimensional hollow tubular porous carbon (SCPC) was prepared from straw cellulose waste through a self‐templating method combined with NaOH activation. Straw cellulose acts both as carbon source and structural template. The obtained SCPC exhibits a 3D hierarchical porous network structure. SCPC has a high specific surface area, a high mesoporosity ratio, and a low resistivity, which make it display excellent electrochemical performance for supercapacitors. SCPC showed a high specific capacitance of 312.57 F g⁻¹ in 6 m KOH at 0.5 A g⁻¹, an excellent rate performance of 281.32 F g⁻¹ even at 15 A g⁻¹, and an outstanding cyclic stability of 92.93 % capacitance retention after 20 000 cycles at 1 A g⁻¹. SCPC‐based supercapacitors can deliver an energy density of 8.67 Wh kg⁻¹ at a power density of 3.50 kW kg⁻¹ in 6 m KOH and an energy density of 28.56 Wh kg⁻¹ at a power density of 14.09 kW kg⁻¹ in 1 m Et₄NBF₄/PC, which demonstrates the possibility of applying SCPC in supercapacitors. This research not only offers a facile and sustainable method for the preparation of hierarchical porous carbon for electrochemical energy storage devices but also provides a highly efficient method for the utilization of biomass waste.

Crystalline and amorphous organic materials are an emergent class of heterogeneous photocatalysts for the generation of hydrogen from water, but a direct correlation between their structures and the resulting properties has not been achieved so far. To make a meaningful comparison between structurally different, yet chemically similar porous polymers, two porous polymorphs of a triazine‐based graphdiyne (TzG) framework are synthesized by a simple, one‐pot homocoupling polymerization reaction using as catalysts Cu^I for TzG_Cu and Pd^II/Cu^I for TzG_Pd/Cu. The polymers form through irreversible coupling reactions and give rise to a crystalline (TzG_Cu) and an amorphous (TzG_Pd/Cu) polymorph. Notably, the crystalline and amorphous polymorphs are narrow‐gap semiconductors with permanent surface areas of 660 m² g⁻¹ and 392 m² g⁻¹, respectively. Hence, both polymers are ideal heterogeneous photocatalysts for water splitting with some of the highest hydrogen evolution rates reported to date (up to 972 μmol h⁻¹ g⁻¹ with and 276 μmol h⁻¹ g⁻¹ without Pt cocatalyst). Crystalline order is found to improve delocalization, whereas the amorphous polymorph requires a cocatalyst for efficient charge transfer. This will need to be considered in future rational design of polymer catalysts and organic electronics.

The high activity and selectivity of zeolites in the cyclisation of unsaturated alcohols is reported for the first time; the details of a reaction mechanism based on quantum chemical calculations are also provided. The high efficiency of zeolites MFI, BEA and FAU in the cyclisation of unsaturated alcohols (cis‐decen‐1‐ol, 6‐methylhept‐5‐en‐2‐ol and 2‐allylphenol) to afford oxygen‐containing heterocyclic rings is demonstrated. The best catalytic performance is found for zeolites with the optimum concentration of Brønsted acid sites (ca. 0.2 mmol g⁻¹) and the minimum number of Lewis acid sites. It is proposed that the efficiency of the catalysts is reduced by the existence of the so‐called dual site, at which a molecule of unsaturated alcohol can simultaneously interact with two acid sites (an OH group with one and the double bond with the other Brønsted site), which increases the interaction strength. The formation of such adsorption complexes leads to a decrease in the catalyst activity because of (i) an increase in the reaction barrier, (ii) an unfavourable conformation and (iii) diffusion limitations. A new procedure for the preparation of tetrahydrofurans and pyrans over zeolite catalysts provides important oxygen‐containing heterocycles with numerous applications.

The present study describes an interesting and practical catalytic system that allows flexible conversion of lignin into aromatic or aliphatic hydrocarbons, depending on the hydrogen partial pressure. A combination of experiment and theory shows that the product distribution between aromatics and aliphatics can be simply tuned by controlling the availability of hydrogen on the catalyst surface. Noticeably, these pathways lead to almost complete oxygen removal from lignin biomass, yielding high‐quality hydrocarbons. Thus, hydrogen–lignin co‐refining by using this catalytic system provides high flexibility in hydrogen storage/consumption towards meeting different regional and temporal demands.

Crystalline and amorphous organic materials are an emergent class of heterogeneous photocatalysts for the generation of hydrogen from water, but a direct correlation between their structures and the resulting properties has not been achieved so far. To make a meaningful comparison between structurally different, yet chemically similar porous polymers, two porous polymorphs of a triazine‐based graphdiyne (TzG) framework are synthesized by a simple, one‐pot homocoupling polymerization reaction using as catalysts Cu^I for TzG_Cu and Pd^II/Cu^I for TzG_Pd/Cu. The polymers form through irreversible coupling reactions and give rise to a crystalline (TzG_Cu) and an amorphous (TzG_Pd/Cu) polymorph. Notably, the crystalline and amorphous polymorphs are narrow‐gap semiconductors with permanent surface areas of 660 m² g⁻¹ and 392 m² g⁻¹, respectively. Hence, both polymers are ideal heterogeneous photocatalysts for water splitting with some of the highest hydrogen evolution rates reported to date (up to 972 μmol h⁻¹ g⁻¹ with and 276 μmol h⁻¹ g⁻¹ without Pt cocatalyst). Crystalline order is found to improve delocalization, whereas the amorphous polymorph requires a cocatalyst for efficient charge transfer. This will need to be considered in future rational design of polymer catalysts and organic electronics.

Zeolites are often investigated as potential adsorbents for CO₂ adsorption and separation. Depending on the zeolite topology and composition (Si/Al ratio and extra‐framework cations), the CO₂ adsorption heats at low coverages vary from −20 to −60 kJ mol⁻¹, and with increasing surface coverage adsorption heats either stay approximately constant or they quickly drop down. Experimental adsorption heats obtained for purely siliceous porous solids and for ion‐exchanged zeolites of the structural type MFI, FER, FAU, LTA, TUN, IMF, and ‐SVR are discussed in light of results of periodic density functional theory calculations corrected for the description of dispersion interactions. Key factors influencing the stability of CO₂ adsorption complexes are identified and discussed at the molecular level. A general model for CO₂ adsorption in zeolites and related materials is proposed and data reported in literature are evaluated with regard to the proposed model.

Pressure effects on regioselectivity and yield of cycloaddition reactions have been shown to exist. Nevertheless, high pressure synthetic applications with subsequent benefits in the production of natural products are limited by the general availability of the equipment. In addition, the virtues and limitations of microflow equipment under standard conditions are well established. Herein, we apply novel‐process‐window (NPWs) principles, such as intensification of intrinsic kinetics of a reaction using high temperature, pressure, and concentration, on azide–alkyne cycloaddition towards synthesis of Rufinamide precursor. We applied three main activation methods (i.e., uncatalyzed batch, uncatalyzed flow, and catalyzed flow) on uncatalyzed and catalyzed azide–alkyne cycloaddition. We compare the performance of two reactors, a specialized autoclave batch reactor for high‐pressure operation up to 1800 bar and a capillary flow reactor (up to 400 bar). A differentiated and comprehensive picture is given for the two reactors and the three methods of activation. Reaction speedup and consequent increases in space–time yields is achieved, while the process window for favorable operation to selectively produce Rufinamide precursor in good yields is widened. The best conditions thus determined are applied to several azide–alkyne cycloadditions to widen the scope of the presented methodology.