Methanolysis Of NaBH4 Research Articles

Various amine functionalized halloysite nanotube as efficient metal free catalysts for H2 generation from sodium borohydride methanolysis

In this work, naturally available clay, halloysite (Hal) nanotube was modified systematically with various types and number of amine groups containing modifying agents and used as catalyst in the methanolysis of sodium borohydride (NaBH4) for hydrogen (H2) production. The modifying agents such as ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), and tris(2-aminoethyl)amine (TAEA), and polyethyleneimine (PEI) were used in Hal nanotube modification followed by protonation with HCl treatments. Various parameters affecting the H2 production rate such as the types of modification agents and/or catalyst types, NaBH4 amount, and the reaction temperature were investigated. The methanolysis of NaBH4 catalyzed by PEI modified and protonated Hal nanotube (H-PEI(750.000)-Hal nanotube) was found to follow first order reaction kinetic with respect to NaBH4 concentration. Interestingly, superior catalytic performances in comparison to the literature for the similar studies were obtained with 16.44kJ/mol, 14.05kJ/mol, and 196.46J/mol·K of activation energy, enthalpy and entropy, respectively for NaBH4 methanolysis catalyzed by H-PEI(750.000)-Hal nanotubes. The hydrogen generation rate of 2218mL/min·g that is comparable to the most of metal nanoparticle catalysts for H-PEI(750.000)-Hal nanotube catalyst was obtained.

H2 generation from NaBH4 methanolysis via magnetic field sensitive ionic liquid coated silica particles as catalyst

Upon the preparation of magnetic (Fe3O4) nanoparticles (NPs), they were coated with amino-functionalized silica (SiO2@NH2) via the modified Stöber method. SiO2 coated Fe3O4 (Fe3O4@SiO2) particles and SiO2@NH2 coated Fe3O4 (Fe3O4@SiO2@NH2) particles were turned into ionic liquid (IL) colloids as Fe3O4@SiO2@NH3+Clˉ, Fe3O4@SiO2@NH3+NO3ˉ and Fe3O4@SiO2@NH3+HSO4ˉ by the treatment of Fe3O4@SiO2@NH2 with hydrochloric acid (HCl), nitric acid (HNO3) and sulfuric acid (H2SO4), respectively. The size of the prepared silica-based particles was approximately 500nm by SEM images, and the zeta potential values varying between −59 and +26mV. The catalytic activity performances of these silica-based particles as catalysts were investigated for H2 generation from methanolysis of NaBH4 in terms of the types of particles, reusability, recyclability, the concentration of NaBH4, and the reaction temperature. Amongst the prepared IL colloids, Fe3O4@SiO2@NH3+Clˉ particles were found to be the most effective catalysts for the methanolysis reaction of NaBH4. The maximum Hydrogen Generation Rate (HGR) value of 13188±196mL H2g−1min−1 was attained at 500mM NaBH4 by using 50mg Fe3O4@SiO2@NH3+Clˉ as catalyst at 25°C. Additionally, turn over frequency (TOF) value was calculated as 43.1±3.1 H2mol (mol of N.min)−1 for Fe3O4@SiO2@NH3+Clˉ under the same reaction conditions. Moreover, activation energy (Ea) values for the methanolysis of NaBH4 using Fe3O4@SiO2@NH3+Clˉ particles as catalyst were found as 32.5±0.5, 39.9±0.3 and 24.4±0.7kJmol−1 in the temperature range of −15–45, −30–0 and 15–45°C, respectively, that are comparable and even better than for most of the metal nanoparticle catalysts used in NaBH4 methanolysis reactions.

Metal-free pyridinium-based polymeric ionic liquids as catalyst for H2 generation from NaBH4

Monodispersed poly(2-vinyl pyridine) (p(2-VP)) polymeric particles were synthesized with a self-emulsion polymerization (SEP) technique. Polymeric ionic liquid (PIL) particles such as poly(2-vinyl pyridine)-ethane (p(2-VP)++C2), poly(2-vinyl pyridine)-butane (p(2-VP)++C4), and poly(2-vinyl pyridine)-hexane (p(2-VP)++C6) particles were then prepared from monodispersed p(2-VP) particles by modifying with 1,2-dibromobutane (DBE) 1,4-dibromobutane (DBB) and 1,6-dibromobutane (DBH), respectively. The hydrodynamic diameter of the prepared particles was found be in the range of 350–400 nm, and the zeta potential of p(2-VP)++Cn (n: 2, 4 and 6) particles were found to be in the range of 26–28 mV. The prepared PIL particles (p(2-VP)++C6 etc.) were shown to be very effective catalysts in H2 generation by methanolysis of NaBH4. Various parameters, such as the effect of modifying agents on PIL particle, the amount of PIL particles, the amount of NaBH4 and temperature, affecting the H2 production rate were investigated. Hydrogen generation rate (HGR) was calculated as 5433 ± 141 mL H2 g−1 min−1 for 50 mg p(2-VP)++C6 particles in the methanolysis of 500 mM NaBH4. The activation energy (Ea) of methanolysis of NaBH4 catalyzed by p(2-VP)++C6 particles was calculated as 20.84 ± 0.76 kJ mol−1, which is much lower than similar studies reported in the literature.

Very fast H2production from the methanolysis of NaBH4by metal-free poly(ethylene imine) microgel catalysts

The polyethyleneimine (PEI) microgels prepared via microemulsion polymerization are protonated by hydrochloric acid treatment (p-PEI) and quaternized (q-PEI) via modification reaction with methyl iodide and with bromo alkanes of different alkyl chain lengths such as 1-bromoethane, 1-bromobutane, 1-bromohexane, and 1-bromooctane. The bare p-PEI and q-PEI microgels are used as catalysts directly without any metal nanoparticles for the methanolysis reaction of sodium borohydride (NaBH4). Various parameters such as the protonation/quaternization reaction on PEI microgels, the amount of catalyst, the amount of NaBH4, and temperature are investigated for their effects on the hydrogen (H2) production rate. The reaction of self-methanolysis of NaBH4 finishes in about 32.5 min, whereas the bare PEI microgel as catalyst finishes the methanolysis of NaBH4 in 22 min. Surprisingly, it is found that when the protonated PEI microgels are used as catalyst, the same methanolysis of NaBH4 is finished in 1.5 min. The highest H2 generation rate value is observed for protonated PEI microgels (10 mg) with 8013 mL of H2/(g of catalyst.min) for the methanolysis of NaBH4. Moreover, activation parameters are also calculated with activation energy value of 23.7 kJ/mol, enthalpy 20.9 kJ/mol, and entropy −158 J/K.mol. Copyright © 2016 John Wiley & Sons, Ltd.

A New Application for Colloidal Silica Particles: Natural, Environmentally Friendly, Low-Cost, and Reusable Catalyst Material for H2 Production from NaBH4 Methanolysis

Metal nanoparticles (NPs) and metal composites (MCs) are generally used as catalysts for the methanolysis reaction of NaBH4. Here, we report the direct use of silica (SiO2) particles as an alternative catalyst for green energy carriers in H2 generation from the methanolysis of NaBH4. The SiO2 particles of different sizes were synthesized using the very well-known Stober method and then treated with various acids such as hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), phosphoric acid (H3PO4), and acetic acid (CH3COOH). The hydrodynamic diameter of prepared SiO2 particles ranged between 200 and 800 nm measured by dynamic light scattering (DLS) with zeta potential values of about −46 and −37 mV. The BET surface area of SiO2 particles was measured between about 4–25 m2 g–1. The catalytic performances of the prepared SiO2 particles in methanolysis of NaBH4 were tested in terms of the effect and the type of treatment agents, acid and base, the hydrodynamic diameter of SiO2 particles, the reu...

Quaternized polymeric microgels as metal free catalyst for H2 production from the methanolysis of sodium borohydride

Abstract Polymeric microgels derived from tris(2-amino ethyl)amine (TAEA) and glycerol diglycidyl ether as p(TAEA-co-GDE) via microemulsion polymerization techniques are protonated by 0.5 M HCl treatment as p(TAEA-co-GDE)-HCl). These microgels are then exposed to anion exchange reactions with differ ionic liquid forming salts, such as potassium thiocyanate (PTC), sodium dicyanamide (SDCA), ammonium hexafluorophosphate (AHFP), and sodium tetrafluoroborate (STFB) in aqueous medium for the preparation of p(TAEA-co-GDE) based ionic liquid colloidal microgels. These anions exchanged p(TAEA-co-GDE) ionic liquid colloids (ILCs) are directly used as catalyst for hydrogen (H2) generation from the methanol solution of sodium borohydride (NaBH4). Various parameters affecting the H2 production rate such as the catalyst types, NaBH4 amount, and the temperature are investigated. It is found that the methanolysis of NaBH4 catalyzed by p(TAEA-co-GDE)-HCl obeys the first order reaction kinetic. The activation energy, enthalpy and entropy of the protonated p(TAEA-co-GDE) microgels are calculated and found as the 30.37 kJ mol−1, 27.96 kJ mol−1, and −148.08 J mol−1 K−1, respectively. Furthermore, the hydrogen generation rate of 3018 mL min−1 g−1 catalyzed by p(TAEA-co-GDE)-HCl catalyst is attained.

An alternative to metal catalysts: Poly(4-vinyl pyridine)-based polymeric ionic liquid catalyst for H2 generation from hydrolysis and methanolysis of NaBH4

Monodispersed p(4-VP) (poly(4-vinyl pyridine)) polymeric particles were synthesized via self-emulsion polymerization and modified with 1,2-dibromobutane 1,4-dibromobutane and 1,6-dibromobutane, to obtain polymeric ionic liquid (PIL) particles of poly(4-vinyl pyridine)-dibromoethane (p(4-VP)++C2), poly(4-vinyl pyridine)-dibromobuthane (p(4-VP)++C4), and poly(4-vinyl pyridine)-dibromohexane (p(4-VP)++C6) particles. Highly monodispersed p(4-VP), p(4-VP)++C2, p(4-VP)++C4 and p(4-VP)++C6 particles were obtained with the sizes of 335 ± 10, 451 ± 17, 432 ± 13 and 443 ± 24 nm, and the zeta potential values of 6.3 ± 0.6, 31.2 ± 2.1, 33.3 ± 1.0 and 35.5 ± 1.1 mV. PIL-metal composites of p(4-VP)++C6-Co p(4-VP)++C6-Ni and p(4-VP)++C6-Fe particles were prepared by reducing CoCl2, NiCl2 and FeCl3 metal salts loaded into p(4-VP)++C6 microgels and then reducing with NaBH4. The prepared PIL-metal composites and PIL particles were used as catalysts in H2 generation from the hydrolysis and methanolysis of NaBH4. It was found that the prepared PIL-metal composites (e.g., p(4-VP)++C6-Co) showed better catalytic performances than PIL particles (e.g., p(4-VP)++C6) for the hydrolysis reaction of NaBH4 whereas, PIL catalytic performances were much better than PIL-metal composites for the methanolysis of NaBH4. Various parameters affecting the hydrolysis and methanolysis reactions of NaBH4 such as the types of PIL/PIL-metal particle, the amount of PIL particles, the amount of NaBH4 and temperature were investigated. A very high hydrogen generation rate (HGR) value for the methanolysis reaction of 500 mM NaBH4 catalyzed by 50 mg p(4-VP)++C6 at 25 °C was calculated as 9125 ± 177 mL H2 (g of catalyst min)−1. Furthermore, very low activation energy (Ea), 13.78 ± 0.23 kJ mol−1 was calculated for the methanolysis of NaBH4 catalyzed by p(4-VP)++C6 at temperatures in the range of 0–40 °C.

Natural microgranular cellulose as alternative catalyst to metal nanoparticles for H2 production from NaBH4 methanolysis

Herein, we report the utilization of microgranular cellulose as a catalyst in virgin and in modified form to be used as metal free catalyst directly in methanolysis reaction of NaBH4 for hydrogen (H2) production. Cellulose was modified with epichlorohydrin and then with diethylenetriamine as Cell-EPC-DETA followed by protonation by hydrochloric acid treatment to obtain Cell-EPC-DETA-HCl. The hydrogen generation rates (HGR) of 408 and 2015mL H2/g catalyst.min were estimated for bare cellulose, and Cell-EPC-DETA, respectively upon their use as catalysts in the methanolysis reaction of NaBH4. Interestingly, HGR value is almost increased 1.6 fold increased, 3215mL H2/(gcatalystmin) upon potations. Besides, the activation energies of Cell-EPC-DETA and Cell-EPC-DETA-HCl were determined as 38.2 and 34.4kJ/mol, respectively that are comparable with the literature. Moreover, the reusability studies of Cell-EPC-DETA and Cell-EPC-DETA-HCl were performed and it was found that there is no decreasing on% conversion for both catalyst, whereas % activity decreased to 61±6, and 65±4% for Cell-EPC-DETA and Cell-EPC-DETA-HCl.

Imidazolium based polymeric ionic liquid microgels as an alternative catalyst to metal catalysts for H2 generation from methanolysis of NaBH4

Ionic liquid monomers (ILMs), 1,n-dialkyl-3,3′-bis-1-vinyl imidazolium bromides, ([C1,n(Vim)2]Br n=4, 6 and 10) were prepared from vinyl imidazole (VI) and dibromo alkanes, dibromobuthane (DBB), dibromohexane (DBH) and dibromodecane (DBD). Then, polymeric ionic liquid (PIL) microgels were synthesized by photo-initiated inverse suspension polymerization technique using these prepared ILMs. The SEM images revealed that the sizes of p(C6VImBr) microgels are in 20–50μm range with the zeta potential values, measured between 15–21mV. The prepared PIL microgels, p(C4VImBr), p(C6VImBr) and p(C10VImBr) were used as catalyst for H2 generation from the methanolysis and hydrolysis of NaBH4. PIL microgels as catalyst were shown great catalytic activity in the methanolysis of NaBH4. Therefore, various parameters such as the type of PIL microgels, the amount of PIL microgels, the concentration of NaBH4, methanolysis temperature of NaBH4 reactions, and the reusability of PIL microgel effecting the H2 generation rates were investigated. The hydrogen generation rate (HGR) of the methanolysis of NaBH4 reaction catalyzed by p(C6VImBr) microgels using 20mL 500mM (2.38wt%) NaBH4 at 25°C was calculated as 5871±100mLH2g−1min−1. Also, the activation energy (Ea) value was found as 34.3±0.8kJmol−1 for H2 generation from methanolysis of NaBH4 catalyzed by p(C6VImBr).

Effect of preparation method on Ni2P/SiO2 catalytic activity for NaBH4 methanolysis and phenol hydrodeoxygenation

A comparative study has been performed on Ni2P/SiO2 catalysts prepared by: (i) conventional temperature-programmed reduction (TPR) of calcined precursors following wet impregnation of the support, (ii) TPR of a sol–gel prepared NiO/SiO2 precursor impregnated with NH4H2PO4 and (iii) a solution-phase reaction in the presence of the SiO2 support using Ni(acac)2 and trioctylphosphine. Catalyst characterization shows that the Ni2P prepared by the solution-phase method has a uniform particle size (7.5 ± 0.8 nm) and H species can easily transfer from the nickel sites to the SiO2 support on this catalyst. These properties result in a high NaBH4 methanolysis to hydrogen activity. In contrast, the sol–gel prepared Ni2P/SiO2 has a relatively high catalytic activity for phenol hydrodeoxygenation due to a higher concentration of Niδ+ species that act as Lewis acid sites and metal sites, and a higher Ni2P crystallinity.

Development of Al2O3 carrier-Ru composite catalyst for hydrogen generation from alkaline NaBH4 hydrolysis

A recyclable and reusable Ru/Al2O3 catalyst is prepared for hydrogen generation from the hydrolysis process of alkaline sodium borohydride (NaBH4) solution. The hydrogen generation rate by the hydrolysis and methanolysis of alkaline NaBH4 was explored as a function of NaOH concentration. Meantime, the byproducts derived from the spent alkaline NaBH4 solution were characterized by X-ray diffraction (XRD), scanning electro microscope/energy dispersive spectrometer (SEM/EDS) and NMR (Nuclear Magnetic Resonance). The effect of NaOH concentration on the hydrogen generation from the hydrolysis of NaBH4 significantly depends on the type of catalysts. With increasing NaOH concentration, the hydrogen generation rates decrease when using ruthenium (Ru) composite as a catalyst. The hydrogen generation rate of the methanolysis of NaBH4 is significantly inhibited in the presence of NaOH as compared with the hydrolysis of NaBH4. The durability test of the Ru/Al2O3 catalyst shows that the hydrogen generation rate decreases with recycling and reuse. The XRD and NMR analysis results show that the borate hydrate (NaBO2 H2O) was derived from the hydrolysis of 20 wt% and 30 wt% NaBH4.

Hydrogen generation from methanolysis of sodium borohydride over Co/Al2O3 catalyst

Co/Al2O3 catalyst is prepared with an impregnation-chemical reduction method and used to catalyze the methanolysis of sodium borohydride (NaBH4) for hydrogen generation. At solution temperature of 0 °C, the methanolysis reaction can be effectively accelerated using Co/Al2O3 catalyst and provide a desirable hydrogen generation rate, which makes it suitable for applications under the circumstance of low environmental temperature. The byproduct of methanolysis reaction is analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The characterization results indicate that methanol can be easily recovered after methanolysis reaction by hydrolysis of the methanolysis byproduct, NaB(OCH3)4. The catalytic activity of Co/Al2O3 towards NaBH4 methanolysis can be further improved by appropriate calcination treatment. The catalytic methanolysis kinetics and catalyst reusability are also studied over the Co/Al2O3 catalyst calcined at the optimized temperature.

Ruthenium immobilized on Al2O3 pellets as a catalyst for hydrogen generation from hydrolysis and methanolysis of sodium borohydride

Ru immobilized Al2O3 pellets were synthesized as a catalyst for hydrogen generation in NaBH4 solutions. Under the Ru/Al2O3 catalysis, the hydrogen generation rate from the hydrolysis and methanolysis of NaBH4 in alkaline solution was explored as a function of NaBH4 concentration and temperature. Meanwhile, the borate byproducts derived from the NaBH4 hydrolysis were characterized by XRD and NMR. The results showed that the hydrogen generation rate depended on NaBH4 concentration for the hydrolysis, but did not for the methanolysis. 10 wt% NaBH4 hydrolysis containing 1 wt% NaOH catalyzed with 0.5 g Ru/Al2O3 could generate hydrogen with a rate of about 65.5 ml min−1 g−1. The productivity and activation energy of hydrogen generation from the NaBH4 hydrolysis were 93% and 41.8 kJ mol−1, and from the NaBH4 methanolysis were 97% and 51.0 kJ mol−1, respectively. The XRD and NMR analyses showed that the species from the hydrolysis byproducts varied with the NaBH4 concentration could be the borax (Na2B4O7·H2O) and sodium borate hydrate (NaBO2·H2O).

Effects of Electrodeposited Co-P Catalysts on the Hydrogen Generation Properties by Methanolysis of NaBH4

not Available.