A Metal- and Solvent-Free Synthesis of aminoalcohols under Continuous Flow Conditions
A Metal- and Solvent-Free Synthesis of aminoalcohols under Continuous Flow Conditions
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Abstract
The use of multifunctional organocatalysts and continuous flow platform are commonplace in modern chemical transformation. Herein, we describe a method for immobilization of trifunctional organocatalysts on porous composite hollow fiber and demonstrate their application as heterogeneous catalyst and continuous-flow microfluidic reactor for chemical transformation. The polyamide imide hollow fibers (PAIHF’s) are functionalized with aminosilanes and bromine source to immobilize covalently hydrogen-bond donor groups (-OH and -NH), and nucleophilic [Br−] species upon the fiber surface and provide trifunctional acid-base-nucleophilic organocatalysts and microfluidic reactors. The cooperative effects of Br/APS/PAIHF trifunctional organocatalysts are elucidated in the CO2 cycloaddition and hydroxyalkylation of aniline under batch and continuous flow synthesis. Our results indicated that the synergistic cooperative effect of trifunctional organocatalyst on PAIHF leads to a maximum 1-(phenylamino)propan-2-ol selectivity of 97.1% at 61% aniline conversion and 0.02 cm3/min flow rate. While knowledge of the acid-base-nucleophilic trifunctional cooperativity is still limited, these findings demonstrate useful structure-property trends that can be used to design more efficient organocatalysts for sustainable chemical transformation.
Gel−Print−Grow: A New Way of 3D Printing Metal−Organic Frameworks.
Gel−Print−Grow: A New Way of 3D Printing Metal−Organic Frameworks.
ABSTRACT:3D printing offers an attractive means of forming structured metal−organic frameworks (MOFs), as this techniqueimparts digital geometric tuning tofit any process column. However, 3D-printed MOF structures are usually formed by suspendingpresynthesized particles into an ink for further processing. This leads to poor rheological properties as MOFs do not bind with inertbinders. Herein, we address this problem by coordinating the MOF secondarily by 3D printing its gelated precursors. Specifically, weproduced a printable sol−gel containing∼70 wt % of HKUST-1 precursors and optimized the in situ growth conditions by varyingthe desolvation temperature and activation solvent. Analysis of the so-called gel-print-grow monoliths’properties as a function of thecoordination variables revealed that desolvating at 120°C produced fully formed MOF particles with comparable diffractive indicesto the parent powder regardless of the activation solvent used. Assessment of the samples’textural properties revealed that washingin acetone or methanol produced the highest surface areas, pore volumes, and CO2adsorption capacities, however, washing withmethanol produced binder swelling and collapse of the printed structure, thereby indicating that washing with acetone was moreeffective overall. This study represents a promising way of 3D printing MOFs and a breakthrough in additive manufacturing, sincethe simple, high-throughput, framework detailed hereinwhereby the synthesis temperature and washing solvent are varied tooptimize MOF coordinationcould easily be applied to other crystallites. As such, it is anticipated that this new and excitingmethod will provide new paths to shape engineer MOFs for applications in energy-intensivefields and beyond.
(PDF) Gel−Print−Grow: A New Way of 3D Printing Metal−Organic Frameworks. Available from: https://www.researchgate.net/publication/346931619_Gel-Print-Grow_A_New_Way_of_3D_Printing_Metal-Organic_Frameworks [accessed Jan 19 2021].
Aminosilane-Grafted SiO2–ZrO2 Polymer Hollow Fibers as Bifunctional Microfluidic Reactor for Tandem Reaction ofGlucose and Fructose to 5-Hydroxymethylfurfural
Aminosilane-Grafted SiO2–ZrO2 Polymer Hollow Fibers as Bifunctional Microfluidic Reactor for Tandem Reaction ofGlucose and Fructose to 5-Hydroxymethylfurfural
Abstract
Abstract
In this study, we demonstrate the concept of tandem reaction for glucose and fructose to 5-hydroxymethylfurfural (HMF) in an aminosilane-grafted SiO2–ZrO2 polyamide–imide hollow fiber that acts as a bifunctional heterogeneous catalyst and microfluidic reactor. The bifunctional catalysts were formed by embedding SiO2 and ZrO2 nanoparticles into polyamide–imide polymer dope that underwent subsequent phase inversion through “dry-jet, wet-quench spinning” process to form hollow fibers, followed by postgrafting with aminosilane to incorporate amine moieties into the hollow fibers. The tandem strategy integrated the first step of glucose isomerization with the subsequent step of dehydration of fructose to HMF over bifunctional Lewis and Brønsted acid sites of hollow fiber microfluidic reactor at different temperatures (100–150 °C) and reaction times (1–8 h). Our results indicated, through optimizing the Lewis to Brønsted acid sites ratio in hollow fiber catalysts, the HMF selectivity was enhanced from 21% to 82% and 21% to 34% by using fructose and glucose as feedstocks, respectively. The effect of water on glucose isomerization and fructose dehydration to HMF was also studied. Investigation of the stability and efficiency of bifunctional catalysts through recycling experiments revealed that this tandem microfluidic system enables precise control of the reaction flow rate, temperature, and time while eliminating the need for an additional catalyst separation step and opening up new opportunities for the conversion of sugar molecules in a continuous-flow system.
Synthesis of Cr, Cu, Ni, and Y‑Doped 3D-Printed ZSM‑5 Monoliths and Their Catalytic Performance for n‑Hexane Cracking.
Synthesis of Cr, Cu, Ni, and Y‑Doped 3D-Printed ZSM‑5 Monoliths and Their Catalytic Performance for n‑Hexane Cracking.
In this work, chromium, copper, nickel, and yttrium-doped 3D-printed ZSM-5 monoliths were synthesized by doping the ZSM-5 zeolite paste with corresponding metal precursors. The physical and acid properties of the metal-doped 3Dprinted ZSM-5 monoliths were systematically characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), Fourier transform-infrared (FT-IR), N2 adsorption, temperature programmed reduction of H2(H2- TPR), and temperature-programmed desorption of ammonia (NH3-TPD) techniques. The characterization of bare and metaldoped monoliths confirmed the presence of metal promoters within the zeolite matrix while their MFI frameworks were retained after doping and printing. It was also found that the metal doping significantly affected the ZSM-5 porosity, acidity, and morphology according to the N2 physisorption, NH3-TPD, and SEM, respectively. The dependence of products selectivities on the conversion of n-hexane and the reaction temperature over 3D-printed ZSM-5 monolith catalysts were reported. Catalytic tests showed that the Cr, Cu and Ni-doped 3D-printed ZSM-5 monolith catalysts exhibited high selectivity toward benzene, toluene, and xylene (BTX), while Y-doped ZSM-5 monolith promoted the light olefins selectivity. The effect of reaction temperature on the cracking activity was also investigated. 3D printing offers a facile and rapid approach for preparing various metal-doped 3D-printed zeolite monoliths. The catalytic findings reported in this investigation highlight the potential of metaldoped 3D-printed zeolite monoliths for use in n-hexane cracking.
Abstract
Patent Multi-Funtionalized Hollow Fiber Organocatalysts
Described herein are multi-functionalized hollow fiber organocatalysts, processes for producing multi-functional-ized hollow fiber organocatalysts, and processes that utilize multi-functionalized hollow fiber organocatalysts for reacting chemicals. A variety of chemical reactions may be enhanced with the multifunctional hollow fiber organocata-lysts. The multi-functionalized hollow fiber organocatalysts are particularly advantageous when used as heterogeneous organocatalysts and continuous-flow reactors,
Abstract
Abstract
The excessive amounts of CO2 emissions to the atmosphere are a critical issue due to the global warming phenomenon. Development of CO2 adsorbents at high temperatures is of paramount importance because of their widespread application. In this investigation, sodium-based borate adsorbents have been developed for the CO2 capture process. Four different sodium precursors (NaOH, NaCl, Na2CO3, and NaNO3) have been employed as a sodium source, their effects on a boric acid material was investigated, and they were tested for CO2 capture application under different temperatures (500–700 °C). The proposed adsorbent materials showed promising results in terms of CO2 capture efficacy. The maximum CO2 uptake (5.45 mmol/g) and the fastest kinetic (90% of its capture uptake achieved within the first minute) have been obtained from the proposed NB4 (NaNO3@H3BO3) material at 600 °C and 1 bar. However, NB2 (NaCl@H3BO3) and the pristine materials (boric acid) showed no capacity toward CO2. Time on stream has also been tested for NB1, NB3, and NB4 after multiple cyclic adsorption–desorption. The materials showed high stability after eight consecutive adsorption–desorption cycles. For further investigation, XRD, FTIR, SEM, and TGA-DSC techniques have been performed for the proposed materials to study their crystalline composition structures, bonding interactions, material degradation, and melting points. The excellent performance of the newly synthesized materials is attributed to the chemical reaction of sodium borate with CO2 with the aid of the molten phase that facilitates CO2 diffusion over the proposed materials. The newly proposed materials could open a new avenue for CO2 capture technology.
The excessive amounts of CO2 emissions to the atmosphere are a critical issue due to the global warming phenomenon. Development of CO2 adsorbents at high temperatures is of paramount importance because of their widespread application. In this investigation, sodium-based borate adsorbents have been developed for the CO2 capture process. Four different sodium precursors (NaOH, NaCl, Na2CO3, and NaNO3) have been employed as a sodium source, their effects on a boric acid material was investigated, and they were tested for CO2 capture application under different temperatures (500–700 °C). The proposed adsorbent materials showed promising results in terms of CO2 capture efficacy. The maximum CO2 uptake (5.45 mmol/g) and the fastest kinetic (90% of its capture uptake achieved within the first minute) have been obtained from the proposed NB4 (NaNO3@H3BO3) material at 600 °C and 1 bar. However, NB2 (NaCl@H3BO3) and the pristine materials (boric acid) showed no capacity toward CO2. Time on stream has also been tested for NB1, NB3, and NB4 after multiple cyclic adsorption–desorption. The materials showed high stability after eight consecutive adsorption–desorption cycles. For further investigation, XRD, FTIR, SEM, and TGA-DSC techniques have been performed for the proposed materials to study their crystalline composition structures, bonding interactions, material degradation, and melting points. The excellent performance of the newly synthesized materials is attributed to the chemical reaction of sodium borate with CO2 with the aid of the molten phase that facilitates CO2 diffusion over the proposed materials. The newly proposed materials could open a new avenue for CO2 capture technology.
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