Hydrogenation of CO2 to form methanol utilizing green hydrogen is a promising route to realizing carbon neutrality. However, the development of catalyst with high activity and selectivity to methanol ...from the CO2 hydrogenation is still a challenge due to the chemical inertness of CO2 and its characteristics of multi-path conversion. Herein, a series of highly active carbon-confining molybdenum sulfide (MoS2@C) catalysts were prepared by the in-situ pyrolysis method. In comparison with the bulk MoS2 and MoS2/C, the stronger interaction between MoS2 and the carbon layer was clearly generated. Under the optimized reaction conditions, MoS2@C showed better catalytic performance and long-term stability. The MoS2@C catalyst could sustain around 32.4% conversion of CO2 with 94.8% selectivity of MeOH for at least 150 h.
In industrial crystallization, spherical crystals have gained increasing interest due to their excellent physicochemical properties, such as high bulk density, flowability, stability, etc. However, ...their formation mechanism is still not well understood and is often oversimplified. In this work, spherical amoxicillin sodium crystals were obtained via a spherulitic growth strategy. It was found that agitation immediately after the addition of crystal seeds was critical for inducing radial noncrystallographic branching and spherulite formation of amoxicillin sodium. Without agitation during the aging period after seed addition, only discrete rod-shaped crystals were obtained. The formation mechanism of amoxicillin sodium spherulites was studied using process analytical technology (PAT) tools, including focused beam reflectance measurement (FBRM) and particle video microscope (PVM). The result was indicative of a three-step morphological evolution process: formation of polycrystalline agglomerates, noncrystallographic branching, and spherulite growth. During this process, agitation immediately after seed addition could help to solute diffusion and induce the agglomeration of small crystals that result from secondary nucleation. The polycrystalline agglomerates serve as the cores for further noncrystallographic branching and growth. On this basis, a new spherulitic growth strategy was proposed by the large addition of crystal seeds as the growth substrates of new branching and spherulite growth. High agitation rates during the aging period can increase the mass ratio of spherulites, and high initial supersaturation can promote branching. Compared with the discrete rod-shaped crystals, spherulites self-regulate the final size greatly up to three times and have a higher bulk density as well as much lower hygroscopicity.
The aqueous solubility of L-tryptophan was measured with a wide range of pH (1.00–12.50) and different monovalent counterions (Na
+
, K
+
, Cl
−
and
NO
3
-
) from 283.15 to 323.15 K by using a static ...equilibrium method. The results showed that the solubility of L-tryptophan increased with increasing temperature and the solubility–pH profile was a “U” shape with the lowest value at the isoelectric point. Additionally, the distribution of the ionic forms of L-tryptophan as a function of pH was obtained using the knowledge of the acid–base equilibria of amino acids, and it was found that the isoelectric points increased with temperature. Moreover, different counterions were introduced by using different acids or bases during pH adjustment and their effect on the solubility of L-tryptophan was investigated, which showed that more L-tryptophan could be dissolved in the presence of K
+
(or
NO
3
-
) than Na
+
(or Cl
−
). Besides, the modified Apelblat model and the NRTL model were successfully used to correlate the aqueous solubility data with all the average relative deviation less than 2.1%.
Florfenicol is an excellent antibiotic and is widely used in animal bacterial diseases. However, its poor water solubility leads to various problems, such as poor absorption and bioavailability. The ...development of nanocrystals is one of the most useful methods for solubilizing florfenicol, which often requires solubility data of florfenicol in different mixed solvents. In this work, the solubility of florfenicol was determined by the gravimetric method in methanol + water, ethanol + water, 1-propanol + water, and isopropanol + water binary solvents at temperatures from 278.15 to 318.15 K. In these four mixed solvents, the solubility of florfenicol increased with the increase in temperature. The solubility of florfenicol in methanol + water mixed solvent increases with the decrease in water ratio, while the solubility of florfenicol in ethanol + water, 1-propanol + water, or isopropanol + water mixed solvents increased first and then decreased with the decrease in water ratio, indicating a cosolvency phenomenon. The modified Apelblat model, CNIBS/R-K model, Jouyban–Acree model, and NRTL model were used to correlate the solubility data of florfenicol in four binary solvents. RMSD values indicated that the calculated values are in good agreement with the experimental solubility data for all four models, among which the CNIBS/R-K model provides the best correlation.
A combination of deep eutectic solvent with ethanol was developed for pretreatment of
to effectively extract lignin and promote the subsequent enzymatic hydrolysis.
In order to further explore the ...optimal conditions for enzymatic hydrolysis, a central composite design method was applied.
The correlation between each factor and glucose yield was obtained, and the optimal conditions was 160°C, 60 min, the ratio of DES to E was 1/1 (mol/mol). The results showed that compared with control, the glucose yield increased by 130.67% under the optimal pretreatment conditions. Furthermore, the specific surface area of biomass was increased by 66.95%, and the content of xylan and lignin was decreased by 86.71% and 85.83%. The correlation between xylan/lignin removal and enzymatic hydrolysis showed that the removal of lignin facilitated the glucose yield more significantly than that of xylan. To further explore the lignin valorization, the structural and antioxidant analysis of recovered lignin revealed that high temperature was favorable for lignin with good antioxidant performance. This pretreatment is a promising method for separating lignin with high antioxidant activity and improving cellulose digestibility.
This work could help to better understand the solvent effects on crystal habits and aspect ratio changes at the molecular level, which provide some guidance for solvent selection in industrial ...crystallization processes. With the catechol crystal habits acquired using both experimental and simulation methods in isopropanol, methyl acetate and ethyl acetate, solvent effects on crystal morphology were explored based on the modified attachment energy model. Firstly, morphologically dominant crystal faces were obtained with the predicted crystal habit in vacuum. Then, modified attachment energies were calculated by the molecular dynamics simulation to modify the crystal shapes in a real solvent environment, and the simulation results were in agreement with the experimental ones. Meanwhile, the surface properties such as roughness and the diffusion coefficient were introduced to analyze the solvent adsorption behaviors and the radial distribution function curves were generated to distinguish diverse types of interactions like hydrogen bonds and van der Waals forces. Results show that the catechol crystal habits were affected by the combination of the attachment energy, surface structures and molecular interaction types. Moreover, the changing aspect ratios of catechol crystals are closely related to the existence of hydrogen bonds which contribute to growth inhibition on specific faces.
•A novel spherical agglomeration technology (SI-SA) is proposed in this work.•SI-SA technology avoids the usage of toxic bridging liquid.•Phase separation and good wettability of organic solvents are ...necessary.•Phase separation is achieved in miscible binary system by adding salts in SI-SA.•Spherical crystals of three drugs in 16 systems are prepared using SI-SA.
In this study, a novel strategy for spherical agglomeration via salt-induced liquid–liquid phase separation (SI–SA) was developed. SI–SA technology achieves phase separation in the miscible binary anti-solvent crystallization system by adding certain amounts of salts, avoiding the use of toxic bridging liquids. Water–organic solvent–salt systems that induced phase separation were selected using phase separation experiments. The wetting performance of the organic solvent was estimated by droplet experiments, and organic solvents with stronger wettability for crystals than water would be selected for further verification. Spherical agglomeration experiments were designed based on the ternary phase diagrams of these selected systems. Water–organic solvent–salt systems of benzoic acid were selected, starting with six organic solvents and four salts. A total number of 16 water–organic solvents–salt systems were effectively predicted using the SI-SA strategy. The in-situ process analysis tool indicated that the formation of spherical particles of benzoic acid underwent a process of crystallization, phase separation, wetting, two-step agglomeration, and consolidation. The stirring rate and mass ratio of salt to final crystals were found to be important for controlling the morphology and particle size of the spherical crystals. The spherical particles of aspirin and salicylic acid were successfully predicted in different systems via SI–SA technology, demonstrating the universality and potential usage of SI–SA technology in industry.
Achieving rapid global agricultural development while maintaining ecological harmony is a major challenge of the new millennium. Meeting this challenge requires the development of efficient and ...environmentally friendly agrochemicals, including pesticides and fertilizers. Molecular assembly, as a promising strategy, has garnered significant attention in recent years for the development of advanced solid-state forms of agrochemicals. In this review, we present the potential and recent advancements of solid-state forms, such as polymorphs, cocrystals/salts, solvates, inclusion compounds, and the amorphous state, for the production of high-efficiency and low-polluting agrochemical products. We provide an overview of the concepts and preparation methods of these solid-state forms, followed by an exploration of their applications in sustainable agriculture. Specifically, we highlight their value in enhancing pesticide solubility, enabling controlled release of chemical fertilizers, and reducing off-target risks. Lastly, we discuss the challenges and prospects associated with the utilization of solid-state forms for the advancement of environmentally friendly and efficient agriculture.
Morphological changes in hydrates during the drying process can cause various potential problems. The crystal properties of caffeine, such as morphology and particle size distribution (PSD), vary ...with drying temperatures. We studied the mechanism of morphological changes in caffeine hydrate and their effect on caking behavior. During the drying process, caffeine crystals maintained their original needle-like morphology at lower temperatures (≤338 K), whereas numerous burrs were formed on the surface at higher temperatures. The morphological changes at different temperatures can be explained by the correlation between isothermal dehydration data and various kinetic models. A lot of burrs peeled away from the crystal surface and the products had wider PSDs and poorer morphology at higher temperatures because the removal of water in the crystal lattices is accelerated and there is not enough time to rearrange the crystal structure. The accelerated caking test indicated that products after agitated drying at higher temperatures exhibited a higher caking tendency.
•Caffeine products drying at higher temperature have a wider PSD and poorer morphology.•Morphological changes of caffeine were caused by various dehydration mechanisms.•High temperatures limit structural rearrangement and cause crystal fragmentation.•Caffeine products drying at higher temperature present greater caking ratios.
Cocrystal engineering is gaining interest across various disciplines since it can effectively tune the properties of solid substances via noncovalent synthesis by introducing new components into the ...lattice. Mechanochemistry is without a doubt the most valuable tool for the research of cocrystals, which combines the pursuit of efficient and sustainable process pathways with the exploration of supramolecular synthons that cannot be discovered using solution methods. In this review, concerning the significance of the mechanochemical synthesis of cocrystals, we begin by outlining the strategies for mechanochemical preparation of cocrystals. We then elaborate on the theoretical mechanisms of the mechanochemically induced formation of cocrystals and their polymorphs. On this foundation, several cross-fields in which mechanochemistry enhances the application value of cocrystal engineering are shown to overcome existing limitations, which are difficult or impossible to access using conventional solution methods. More importantly, we demonstrate that the introduction of new methods, such as cultivating single crystals from melt microdroplets, and new techniques, such as microelectron diffraction (Micro-ED), has harmoniously united the fields of cocrystal engineering and mechanochemistry. Finally, a brief conclusion and outlook are presented, including current challenges and future opportunities for the cooperation of mechanochemistry and cocrystal engineering.
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