In the search of Ni based metal-organic frameworks (MOFs) containing paddle-wheel type building units, three chemical systems Ni(2+)/H(n)L/base/solvent with H(n)L = H(3)BTC (1,3,5-benzenetricarboxylic acid), H(3)BTB (4,4',4'',-benzene-1,3,5-triyl-tris(benzoic acid)), and H(2)BDC (terephthalic acid) were investigated using high-throughput (HT) methods. In addition to the conventional heating, for the first time HT microwave assisted synthesis of MOFs was carried out. Six new compounds were discovered, and their fields of formation were established. In the first system, H(3)BTC was employed and a comprehensive HT-screening of compositional and process parameters was conducted. The synthesis condition for the Ni paddle-wheel unit was determined and two compounds [Ni(3)(BTC)(2)(Me(2)NH)(3)]·(DMF)(4)(H(2)O)(4) (1a) and [Ni(6)(BTC)(2)(DMF)(6)(HCOO)(6)] (1b) were discovered (Me(2)NH = dimethylamine, DMF = dimethylformamide). In the second system, the use of the extended tritopic linker H(3)BTB and the synthesis conditions for the paddle-wheel units led to the porous MOF, [Ni(3)(BTB)(2)(2-MeIm)(1.5)(H(2)O)(1.5)]·(DMF)(9)(H(2)O)(6.5) (2), (2-MeIm = 2-methylimidazole). This compound shows a selective adsorption of H(2)O and H(2) with a strong hysteresis. In the third system, H(2)BDC was used, and the base (DABCO) was incorporated as a bridging ligand into all structures. Thus, two pillared layered porous MOFs [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(1.5) (3a) and [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(4) (3b) as well as a layered compound [Ni(BDC)(DABCO)]·(DMF)(1.5)(H(2)O)(2) (3c) were isolated. The 3a and 3b polymorphs of the [Ni(2)(BDC)(2)(DABCO)] framework can be selectively synthesized. The combination of microwave assisted heating, low overall concentration, stirring of the reaction mixtures, and an excess of DABCO yields a highly crystalline pure phase of 3b. The fields of formation of all compounds were established, and scale-up was successfully performed for 1b, 2, 3a, 3b, and 3c. All compounds were structurally characterized. In addition to IR, elemental and TG analyses, gas and vapor sorption experiments were carried out.
The hydrothermal gasification is a promising process to produce hydrogen from biomass with high water content. In a lot of cases, this biomass may contain proteins, for example, in residues from the food industry or sewage sludge. In Part I of this serial, experiments on hydrothermal gasification of protein containing biomass (zoo mass) have been reported. This biomass produces lower gas yields than biomass originating exclusively from plants (phyto mass). To understand these findings, experiments with model compounds are necessary. Here, such experiments with model compounds in a tubular and a batch reactor are described. The model system for the phyto mass is glucose with a potassium salt, and the model system for the zoo mass is glucose, potassium salt, and the amino acid alanine. The model systems show a lower gas yield in the presence of alanine. So the presence of alanine in the model system has a similar effect to the presence of proteins in biomass. Additionally, the gas composition and the concentration of selected key compounds are slightly changed by alanine addition. Likely, consecutive products of carbohydrate and protein degradation react with each other. In such Maillard reactions, free radical scavengers might be formed, reducing the reaction rate of free radical chain reactions that are highly relevant for gas formation. Therefore, the gas yield is lower in the presence of proteins or amino acids compared with systems without these compounds. In addition, experiments with real biomass in a batch reactor were reported to verify the assumption of Maillard products reducing free radical reactions. As an example, the addition of urea to phyto mass leads to a decrease of the gas yield to a value similar to that found for zoo mass.
The reaction of intermediates formed during hydrothermal biomass gasification (HBG) with each other or with hydrogen produced by the water-gas shift reaction has a significant influence on the process. To understand these reactions, the conversion of different C4 compounds (1-butanol, 1-butanal, cis-butendiol) was investigated in a batch reactor. These compounds carry different functional groups also found in intermediates of HBG. All compounds react to make products with aromatic ring systems, which shows that the intermediates can react with each other and aromatic rings are formed independently of the functional groups. The HBG intermediates can also react with hydrogen formed via the water-gas shift reaction (CO + H 2 O 5 CO 2 + H 2 ). This is shown by the reaction of deuterated glucose in H 2 O. The reaction of hydrogen originating from water leads to the formation of C-H bonds not present in the feedstock.
A high-throughput (HT) investigation using the rigid bifunctional ligand 4-phosphonobenzenesulfonic acid, H 2 O 3 P-C 6 H 4 -SO 3 H (H 3 L), generated five new phosphonatobenzenesulfonates with copper(II) or lead(II) ions. A comprehensive HT study comprising the screenings of different metal ions, metal salt types and the synthesis optimization were conducted whereby the influence of pH and molar ratios M 2+
A new copper(II) phosphonatobenzenesulfonate incorporating 4,4'-bipyridine (4,4'-bipy) as auxiliary ligand has been discovered through systematic high-throughput (HT) screening of the system Cu(NO 3 ) 2 ·3H 2 O/H 2 O 3 PC 6 H 4 SO 3 H/4,4'-bipy using different solvents. The hydrothermal synthesis of [Cu(HO 3 PC 6 H 4 SO 3 )(C 10 H 8 N 2 )]·H 2 O (1) was further optimized by screening various copper(II) salts. The crystal structure of 1 was determined by single-crystal X-ray diffraction and unveiled the presence of isolated sixfold coordinated Jahn-Teller-distorted Cu 2+ ions. The isolated CuN 2 O 4 octahedra are interconnected by phosphonate and sulfonate groups to form chains along the c-axis. The organic groups, namely phenyl rings and 4,4'-bipy molecules cross-link the chains into a three-dimensional framework. Water
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.