Alkali lignin, a significant waste resource from the pulp and paper industry, is produced in large quantities each year, but its utilization remains limited. This study focuses on the cleavage of –OCH3 groups attached to the aromatic ring in alkali lignin to obtain demethylated alkali lignin nanospheres (DAL-NPs) enriched with aromatic hydroxyl (Ar–OH) groups. These DAL-NPs are intended for the efficient adsorption of NH3. Qualitative and quantitative characterization of alkali lignin, both pre- and post-demethylation, was performed using Fourier transform infrared spectroscopy and 1H NMR. The analysis revealed a reduction in methoxy groups and an increase in Ar–OH groups in the DAL-NPs. The NH3 adsorption experiment demonstrated that the DAL-NPs exhibited a rapid and high adsorption capacity, reaching an NH3 uptake capacity of 10.0 mmol g–1 within 0.42 min at 298 K and 1.0 bar. In addition, the DAL-NPs displayed superior selectivity based on the ideal adsorption solution theory for 10% NH3/90% N2 (3252) and 10% NH3/90% CO2 (175) at 298 K and 1.0 bar. The DAL-NPs also demonstrated reversibility and stability during 10 adsorption–desorption cycles. The DAL-NP adsorbent possesses exceptional properties, such as abundance and low cost, rapid and efficient adsorption, reversibility, and stability, making it a promising solid adsorbent for effective NH3 adsorption in the ammonia process. 

Demethylation of Waste Alkali Lignin for Rapid and Efficient Ammonia Adsorption

Abstract A variety of Pd‐catalyzed reactions are carried out with palladium carboxylates in the presence of carboxylic acids and/or alkali metal carboxylates. This review is Part A of three reviews highlighting the dependence of the efficiency of the formation of the different C−C bonds on the nature of the carboxylate unit. Part A concerns inter‐ and intramolecular reactions leading to the formation of a C( sp 2 )−C( sp 2 ), C( sp 2 )−C( sp 3 ) or C( sp 3 )−C( sp 3 ) bond. The variety of procedures and additives is presented as well as the reaction mechanisms with, as far as possible, personal comments. 

Palladium Catalysis: Dependence of the Efficiency of C–C Bond Formation on Carboxylate Ligand and Alkali Metal Carboxylate or Carboxylic Acid Additive. Part A: the C(sp2)–C(sp2), C(sp2)–C(sp3) and C(sp3)–C(sp3) Bonds

Pd(II)/Lewis acid catalyzed oxidative C–H olefination/annulation with dioxygen to construct dihydrophenanthridines and its mechanistic studies

Pd(II)/Lewis Acid Catalyzed Intramolecular Oxidative C–H Amination to Construct Carbazoles with Dioxygen

Benzoxazole and benzothiazole moiety have been used as innate directing handles for Pd(II)- and Ru(II)-catalyzed C–H arylation of bio-relevant heterocycles, 2-arylbenzoxazole and 2-arylbenzothiazole with diverse iodoarenes, following a complementarity of palladium-ruthenium catalysts. The induction of σ-donor ligands, such as N,N-dimethylacetamide to Pd(II) catalytic cycle and σ-donor/π-acceptor ligand, such as PPh3 to Ru(II) catalytic cycle enhances the arylation rate significantly and governed by the C–H acidity of C2-aryl ring of 2-arylbenzoxazole/2-arylbenzothiazole. The approaches have a broad substrate scope with respect to coupling partners to accommodate electron-neutral, electron-rich as well as electron-deficient iodoarenes plus C2-aryl unit of 2-arylbenzoxazoles/2-arylbenzothiazoles, exhibit a high degree of siteselectivity at ortho-C–H position, afford only mono-arylated derivatives in decent yields, functional groups tolerant, and applicable to ‘gram-scale’ production.

Benzoxazole/benzothiazole as an innate directing group for palladium- and ruthenium-catalyzed complementary C–H arylation: Functionalization of bio-relevant heterocyclic scaffolds

Currently available liquid absorbents and porous adsorbents for capturing NH3 are often unfavorable in terms of possessing high stability and reusability. Herein, three novel sulfonated phenol–formaldehyde (SPF) resins with almost non-porosity were prepared through a facile polymerization of various phenol sulfonates with formaldehyde and applied to the adsorption of NH3. It is demonstrated that the SPF–Na resin displayed excellent reversibility and good stability for efficient NH3 adsorption (12.87 mmol·g–1) and superior ideal adsorption solution theory selectivities for 3% NH3/97% N2 (5076) and 3% NH3/97% H2 (2619) at 298.2 K and 1.0 bar even in 20 adsorption–desorption cycles, whereas common PF resin only achieved a very low capacity of 1.9 mmol·g–1. Column breakthrough results further confirmed that the SPF–Na resin showed good performance in selective adsorption of 3% NH3 in the mixture of NH3/N2/H2. Nonporous SPF resins with high stability, desired capacity, and outstanding reversibility are perceived as promising solid adsorbents for effectively capturing NH3 in the ammonia industry. 

Sulfonated Phenol–Formaldehyde Resins for Highly Efficient, Selective, and Reversible Adsorption of NH3

Direct C-H activation and functionalization offer a convenient protocol for pharmaceutical and material syntheses. Although versatile mechanisms have been proposed to depict transition-metal-catalyzed C-H activation, to date, the shared key agostic hydrogen intermediate in several major mechanisms has not been observed yet, which apparently puzzles the mechanism-based catalyst design. This work reports the direct observations of this intermediate in Pd(II)/Sc(III)-catalyzed C-H activation of acetanilides, and its stability and reactivity in C-H activation are investigated. Remarkably, this intermediate is only observed in electron-rich acetanilides, and the meta-substituent with increased σm constant generally accelerates C-H activation, a characteristic of the base-assisted C-H activation mechanism. This study has unveiled the masks of this intermediate with an understanding of its first-hand physicochemical properties, shedding new light on mechanism-based catalyst design.

Observing the Agostic Hydrogen in Pd(II)-Catalyzed Aromatic C-H Activation.

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Sulfonated Phenol–Formaldehyde Resins for Highly Efficient, Selective, and Reversible Adsorption of NH3

Observing the Agostic Hydrogen in Pd(II)-Catalyzed Aromatic C-H Activation.