Addition Of Metal Chlorides Research Articles

Toward understanding the reactivity and catalytic mechanism of coal pyrolysis with metal chloride modification

Catalytic pyrolysis of Zhundong coal over three metal chlorides (NaCl, CaCl2, and FeCl3) was investigated via a thermogravimetric analyzer and a fixed bed reactor in this study. The structural features of the chars were examined using X-ray diffraction, scanning electron microscopy and N2 adsorption analyzer, and the pyrolysis mechanisms regarding the cleavage of bonds were proposed. The results demonstrate that all three chlorides have a beneficial effect on the production of CH4/H2 and are ranked according to catalysis ability as follows: NaCl > FeCl3 > CaCl2; the opposite effect is observed for the production of CO. The addition of metal chlorides results in a highly rough surface and a low degree of graphitization. Moreover, the sample with added FeCl3 has a more porous and disintegrated structure than those with added NaCl and CaCl2, and the pores and cracks are caused by gas release during the transformation process of FeCl3 to Fe2O3. In terms of the catalytic mechanism, FeCl3 differs from NaCl and CaCl2 in coal pyrolysis. FeCl3 is converted to Fe2O3 to promote the formation of free radicals during the pyrolysis process, while Na/Ca species are involved in a repeated process of bond formation and bond breakage between the species and the coal matrix.

The effect of alkali metal chlorides and temperature on acid-hydrolysis residual pyrolysis products

Acid-hydrolysis residual (AHR) offers significant potential for harvesting chemical energy with simultaneous reduction of environmental pollution, providing carbon neutral (or even carbon negative) sustained energy production, energy security and alleviating social concerns associated with the wastes. In this study, the different effects of intrinsic and extrinsic K and Na were compared firstly. In addition, the effect of different content of alkali metal chlorides doped into AHR and temperature on pyrolysis products were investigated, especially for the phenolic products in bio-oil, along with the grey relational analysis. The results showed that KCl and NaCl promoted the generation of char and gas at the expense of the bio-oil yield. While, addition of KCl and NaCl could increase the yields of total phenolic species. Specifically, the yields of phenols and hydroxy phenols increased, while the guaiacols and syringols content decreased. The effect of KCl on the distribution of pyrolysis products and phenolic species was somewhat greater than NaCl, especially for bio-oil yield. The increasing of pyrolysis temperature would increase gas yield and reduce the char yield. While the bio-oil yield was peaked at 650 ℃. Besides, higher temperature restrained the generation of syringols and promoted the generation of phenols and hydroxy phenols. The grey relational analysis of KCl and temperature showed that KCl content was the major factor in the generation of bio-oil in pyrolysis process, while temperature played more notable role on the yields of total phenolic species, phenols, hydroxy phenols, guaiacols and syringols. The addition of alkali metal chlorides could promote the pyrolysis process and enhance the maximum lower heating value (LHV) of pyrolysis gas, especially the addition of NaCl. The optimal value of addition amount of KCl and NaCl was found to be 2 wt.% and 0.5 wt.%, respectively. Besides, the addition of KCl and NaCl could improve pore quality and activation of AHR pyrolysis char. Based on the pyrolysis products from cellulose, it can be proposed that cellulose has two main pathway depending on the alkali metal chlorides content.

Catalytic effect of metal chlorides on coal pyrolysis and gasification part I. Combined TG-FTIR study for coal pyrolysis

The catalytic effects of three metal chlorides, including KCl, ZnCl2, and MnCl2, on the pyrolysis of lignite were investigated by thermogravimetry (TG) coupled with Fourier transform infrared (TG-FTIR) analysis from 105°C to 1000°C at a heating rate of 10°C/min. The procedure of acid washing and the addition of metal chlorides had little effect on the structure of coal. The catalytic effect of inherent mineral became obvious only when the temperature was higher than 660°C. The addition of metal chlorides promoted the pyrolysis process when the temperature was lower than 400°C and higher than the critical temperature. DTG curve was fitted into six sub-curves to further analyze the pyrolysis process especially the breakage of chemical bonds. All three metal chlorides had a good catalytic effect on the quantity of CH4 production but the opposite effect on CO production. MnCl2 was the most favorable metal chloride for the production of CH4. The catalytic mechanism of KCl was different from that of MnCl2 and ZnCl2 on coal pyrolysis.

A Systematic Study of the Effects of Metal Chloride Additives on H2 Desorption Properties of Ammonia Borane

The effects of metal-based additives in a wide range of elements doping into ammonia borane (AB) were systematically investigated. Pure transition metals in period 4 and total of 17 metal chlorides were selected as additives and ball-milled with AB. Metal chloride additives were effective to decrease H2 desorption temperature and the amounts of byproduct gas emissions of AB, whereas pure transition metals did not show any ability because they did not work as Lewis acids. The strong correlation between H2 desorption temperature and the Pauling electronegativity of metal (χp) was observed. Mn+ of MCln would work as Lewis acid to initiate the AB dehydrocoupling reaction. The amount of NH3 emission was correlated with the ionic radius of M, suggesting MCln·mNH3 complexes be formed in this system. AB–CuCl2 and AB–AgCl mixtures showed the similar H2 desorption processes. The Cl-containing intermediate phase would destabilize AB during reaction.

Foam stabilisation using surfactant exfoliated graphene

Liquid–air foams have been stabilised using a suspension of graphene particles at very low particle loadings. The suspension was prepared through the liquid phase exfoliation of graphite in the presence of the non-ionic tri-block surfactant, Pluronic® F108. The graphene particles possess an extremely high aspect ratio, with lateral dimensions of between 0.1 and 1.3μm as evidenced by TEM imaging. The particles were shown to exhibit a number of other properties known to favour stabilisation of foam structures. Particle surface activity was confirmed through surface tension measurements, suggesting the particles favour adsorption at the air–water interface. The evolution of bubble size distributions over time indicated the presence of particles yielded improvements to foam stability due to a reduction in disproportionation. Foam stability measurements showed a non-linear relationship between foam half-life and graphene concentration, indicative of the rate at which particles adsorb at bubble surfaces. The wettability of the graphene particles was altered upon addition of alkali metal chlorides, with the stability of the foams being enhanced according to the series Na+>Li+>K+>Cs+. This effect is indicative of the relative hydration capacity of each salt with respect to the surfactant, which is adsorbed along the graphene plane as a result of the exfoliation process. Thus, surfactant exfoliated graphene particles exhibit a number of different features that demonstrate efficient application of high-aspect ratio particles in the customisation and enhancement of foams.

Molten Salt Spectroscopy for Quantification of Radiative Absorption in Novel Metal Chloride-Enhanced Thermal Storage Media

This study describes the development and characterization of novel high-temperature thermal storage media, based on inclusion of transition metal chlorides in the potassium–sodium chloride eutectic system, (K–Na)Cl (melting temperature of 657 °C, latent heat of 278 J/g). At the melting temperature of (K–Na)Cl, infrared (IR) radiation can play a major role in the overall heat transfer process—90% of spectral blackbody radiation falls in the range of 2–13 μm. The authors propose inclusion of small amounts (less than 0.2 wt.%) of IR-active transition metal chlorides to increase radiative absorption and thereby enhance heat transfer rates. A new IR-reflectance apparatus was developed to allow for determination of the spectral absorption coefficient of the newly formulated phase-change materials (PCMs) in the molten state. The apparatus consisted of an alumina crucible coated at the bottom with a reflective (platinum) or absorptive (graphite) surface, a heated ceramic crucible-holder, and a combination of zinc sulfide (ZnS) and zinc selenide (ZnSe) windows for containment of the salt and allowance of inert purge gas flow. Using this apparatus, IR spectra were obtained for various transition metal chloride additives in (K–Na)Cl and improved IR activity, and radiative transfer properties were quantified. Further, thermophysical properties relevant to thermal energy storage (i.e., melting temperature and latent heat) are measured for the pure and additive-enhanced thermal storage media.

Overexpression of afsR and Optimization of Metal Chloride to Improve Lomofungin Production in Streptomyces lomondensis S015

As a global regulatory gene in Streptomyces, afsR can activate the biosynthesis of many secondary metabolites. The effect of afsR on the biosynthesis of a phenazine metabolite, lomofungin, was studied in Streptomyces lomondensis S015. There was a 2.5-fold increase of lomofungin production in the afsR-overexpressing strain of S. lomondensis S015 N1 compared with the wild-type strain. Meanwhile, the transcription levels of afsR and two important genes involved in the biosynthesis of lomofungin (i.e., phzC and phzE) were significantly upregulated in S. lomondensis S015 N1. The optimization of metal chlorides was investigated to further increase the production of lomofungin in the afsR-overexpressing strain. The addition of different metal chlorides to S. lomondensis S015 N1 cultivations showed that CaCl2, FeCl2, and MnCl2 led to an increase in lomofungin biosynthesis. The optimum concentrations of these metal chlorides were obtained using response surface methodology. CaCl2 (0.04 mM), FeCl2 (0.33 mM), and MnCl2 (0.38 mM) gave a maximum lomofungin production titer of 318.0 ± 10.7 mg/l, which was a 4.1-fold increase compared with that of S. lomondensis S015 N1 without the addition of a metal chloride. This work demonstrates that the biosynthesis of phenazine metabolites can be induced by afsR. The results also indicate that metal chlorides addition might be a simple and useful strategy for improving the production of other phenazine metabolites in Streptomyces.

Pyrolysis treatment of waste polyurethane foam in the presence of metallic compounds

The influence of the presence of some metal salts and oxides on pyrolysis of polyurethane (PUR) foam has been studied with thermogravimetric analysis, TGA, and a lab-scale reactor. The pyrolysis products of the latter at 800°C were analysed with gas chromatography–mass spectrometry, XRD and ion metre. The addition of metal chloride decreased the yield of liquid products, and increased the yield of carbonaceous residue, which could be ascribed to the Lewis acidic nature of the examined salts. Zinc chloride exhibited especially high ability to fix carbon in the polymer as char; the carbon yield reached more than 30% of the initial carbon in the sample. This is considerably high, as essentially no residue remained in the lab-scale pyrolysis of polyurethane foam at 800°C. As for the nitrogen-containing pyrolysis products, the addition of metallic compounds enhanced the yield of ammonia. This result implies that the addition of metallic compounds is effective for the emission control of nitrogen-containing products from polyurethane foam.

Conversion of xylose and xylan into furfural in biorenewable choline chloride–oxalic acid deep eutectic solvent with the addition of metal chloride

An environmentally benign processing approach for furfural production from xylose and xylan under very mild conditions (353–373 K) was developed with the addition of metal chlorides in ChCl–oxalic acid (a deep eutectic solvent (DES)) synthesized from cheap and renewable starting materials). ChCl–oxalic acid acted as both a Bronsted acid catalyst and a reaction medium in this catalytic route. In addition, a biphasic system with methyl isobutyl ketone as an extracting reagent (DES/MIBK) to further increase furfural yield was also proposed. This processing approach for producing furfural eliminated the large energy consumption for high pressure saturated steam and the generation of acidic effluent, which was very difficult to handle. The whole catalytic system was more environmentally friendly compared with the commercial process for furfural production.

Bio-oil production by fast pyrolysis of cellulose/polyethylene mixtures in the presence of metal chloride

Cellulose/polyethylene mixture (3:1 w/w) and Tetra Pak wastes with and without metal chloride (ZnCl2, AlCl3, CuCl2, FeCl3) addition were subjected to a fast pyrolysis process at 350–500 °C and heating rate 100 °C/s to evaluate the possibility of liquid product formation with a high yield. The addition of zinc, aluminum, iron and copper chlorides has influenced the range of samples decomposition as well as the chemical composition of resulting pyrolytic oils. It was found that formation of levoglucosan, the main product of cellulose thermal decomposition, and phenol and its derivatives decreased in a presence of metal chlorides. Non-catalytic fast pyrolysis of polyethylene leads to the formation of solid long chain hydrocarbons, whereas the addition of metal chlorides promotes the formation of more liquid hydrocarbons.

Experimental evaluation of water mist with metal chloride additives for suppressing CH4/air cup-burner flames

In order to investigate the fire suppression effectiveness of water mist with metal chloride additives, ultrafine water mists of these salts with diameters about 10μm were introduced into CH4/air non-premixed flame in the cup burner. Results showed that these droplets hard to make itself to the flame front under the cup burner flow conditions functioned as a carrier of the vaporized solid particles or its decomposed materials. The metal chloride improved fire suppression efficacy of water mist which were affected by the type and concentration of metal chloride. On a mass basis, there is a fire suppression effectiveness relationship of MgCl2<CaCl2<NaCl<KCl<MnCl2<FeCl2. The flame suppression ability of water solution/metal chlorides improves as the concentration of metal chlorides increase. However, upper additive limits exist due to the associated limiting vapour pressure of the additive.

The Chameleon-Like Nature of Zwitterionic Micelles: Effect of Cation Binding

Addition of salts, especially perchlorates, to zwitterionic micelles of SB3-14, C(14)H(29)NMe(2)(+)(CH(2))(3)SO(3)(-), induces anionic character and uptake of H(3)O(+) by SB3-14 micelles. Thus, the addition of alkali metal perchlorates accelerates the acid hydrolysis of 2-(p-heptoxyphenyl)-1,3-dioxolane, HPD, in the presence of SB3-14 micelles, which depends on the local proton concentration at the micelle surface. The addition of metal chlorides to solutions of such perchlorate-modified SB3-14 micelles decreases both the negative zeta potential of the micelles and the observed rate constant for acid hydrolysis of HPD. The effect of the monovalent cations Li(+), Na(+), and K(+) is smaller than that of the divalent cations Be(2+), Mg(2+), and Ca(2+), and much smaller than that of the trivalent cations Al(3+), La(3+), and Er(3+). The major factor responsible for this cation valence dependence of these effects is shown to be electrostatic in nature, reflecting the strong dependence of the micellar surface potential on the cation valence. The fact that the salt effects are not identical after correction for the electrostatic effects indicates that additional secondary nonelectrostatic effects may contribute as well.

The uptake of halogen (HF, HCl, HBr and HI) and nitric (HNO3) acids into acidic sulphate particles in quiescent volcanic plumes

The uptake of halogen and nitric acids into acidic sulphate particles has important implications for volcano monitoring and the environmental geochemistry of volcanic emissions. Using the Extended Aerosol Inorganics Model (E-AIM) for HCl, HBr and HNO3, combined with a simple three-parameter model for HF and HI, we show that equilibrium partitioning of halogen and nitric acids into sulphate particles is maximised at high relative humidity (RH), low temperature, low plume dilution (i.e., near-source) and high SO42−/SO2. The addition of metal chlorides (i.e., NaCl) enhances acidic gas partitioning at high RH, but diminishes acidic gas partitioning at low RH due to a decrease in the water content of particles and the formation of Na sulphate salts. We predict that acidic gas partitioning is quantitatively significant (>1%) only in cool humid conditions (e.g., >80% RH at 298K), adding confidence to spectroscopic and/or electrochemical determinations of gas ratios (e.g., SO2/HCl, HCl/HF) for volcano monitoring. However, acidic gas partitioning remains environmentally important over a wide range of conditions because of the significant variability in the amounts of acidic gases in particle form (Cl−(aq), Br−(aq), I−(aq), NO3−(aq), HF(aq)). This may result in diurnal and seasonal changes in acidic gas deposition downwind of the volcano.

Direct production of hydroxymethylfurfural from raw grape berry biomass using ionic liquids and metal chlorides

We report for the first time the direct conversion of raw grape berry biomass to hydroxymethylfurfural (HMF) using ionic liquid solvents with metal chloride catalysts. Exploiting raw plant biomass as a biorefinery feedstock is innovative for sustainable chemical industry. The use of the raw biomass to synthesize compounds can indeed lead to less energy consumption and less CO2 emissions. Using raw plant biomass skips pretreatment steps that are required to produce biomaterials such as carbohydrates or cellulosic biomass. Here, grape berry biomass was used as a raw chemical feedstock for the production of hydroxymethylfurfural, a key platform intermediate for syntheses of future renewable biofuels. We examined 3 ionic liquid solvents, 3 reaction temperatures, 5 chloride catalysts, and 5 concentrations of HCl. We found an increasing HMF yields depending on reaction conditions. 1-octyl-3-methylimidazolium chloride was most effective for HMF synthesis. Addition of HCl or metal chlorides alone showed little improvement. The highest HMF yield of about 100 mg HMF per mL of grape biomass extract was obtained using 0.3 M HCl, [OMIM]Cl, and CrCl2 at 100°C for 3 h. Our study provides a model system of sustainable production of valuable compounds from raw plant biomass.

Effect of alkali and alkaline-earth chloride addition on electrolytic reduction of UO 2 in LiCl salt bath

The electrolytic reduction process of actinide oxides in a LiCl salt bath at 923 K has been developed for nuclear fuel reprocessing. Since some salt-soluble fission products, such as Cs, Sr and Ba, accumulate in the LiCl salt bath, their effect on UO 2 reduction was investigated. In the experiments, UO 2 specimens were reduced by potential- or current-controlled electrolysis in various LiCl salt baths containing up to 30 mol% of KCl, CsCl, SrCl 2 or BaCl 2. The rate of UO 2 reduction in a LiCl salt bath was considerably decreased by the addition of alkali metal chlorides (KCl and CsCl) and slightly decreased by BaCl 2 addition. SrCl 2 addition had no appreciable effect. It was suggested that the diffusion of O 2− ions from the inside of UO 2 specimens to the bulk salt determined the reduction rate during the electrolysis and that the effect of salt composition was related to the solubility of O 2− ions in the salt bath.

Early–late heterobimetallic Rh–Ti and Rh–Zr complexes via addition of early metal chlorides to mono- and divalent rhodium

Addition of TiCl(4) or ZrCl(4) to (PNP)Rh(CH(2)==CH(t)Bu) (1) rapidly gives complexes (PNP)Rh(MCl(3))(Cl) (M = Ti, 2; Zr, 3) in 75-77% yield (PNP = (4-Me-2-((i)Pr(2)P)-C(6)H(3))(2)N). Compound 2 can also be synthesized via a reaction of (PNP)RhCl with TiCl(3) or of (PNP)TiCl(3) with 1/2 [(cod)RhCl](2).

Enhanced Dehydrogenation Properties of Modified Mg(NH2)2−LiBH4 Composites

Promotion of dehydrogenation based on a combination of [BH] and [NH] sources has been demonstrated to be an effective approach in developing an advanced borohydride/amide multicompound hydrogen storage system. In this article, the hydrogen storage properties of Mg(NH2)2−LiBH4 composite are studied systematically. It has been shown that the Mg(NH2)2−LiBH4 binary system exhibits an onset dehydrogenation temperature of 250 °C, accompanied by an emission of 5.5 mol % ammonia. Further investigation has revealed that addition of metal chlorides results in significant improvement of the dehydrogenation of Mg(NH2)2−LiBH4. In particular, with NiCl2 addition up to 20 wt %, the modified composite exhibits more favorable thermodynamics, as demonstrated by an onset dehydrogenation temperature as low as 60 °C, accompanied by the suppressed evolution of byproduct NH3 (2 mol %), which enables this modified system to release 7.3 wt % hydrogen in the temperature range of 60−400 °C, which is vastly superior compared with the dehydrogenation of Mg(NH2)2−LiBH4 alone. X-ray diffraction results indicate that the presence of Mg(NH2)2 results in an accelerated exchange reaction between LiBH4 and NiCl2, which may be the dominant reason for the improved thermodynamics and kinetics in the NiCl2-added Mg(NH2)2−LiBH4 system.

Hydrothermal conversion of FAU zeolite into aluminous MTN zeolite

The hydrothermal conversion of FAU zeolite into aluminous MTN zeolite is described here. In the presence of both benzyltrimethylammonium hydroxide (BTMAOH) and sodium chloride (NaCl) the highly crystalline and pure MTN zeolites with Si/Al ratios of 21-23 could be obtained from the hydrothermal conversion of FAU zeolite. Based on powder XRD refinement and 13C CP/MAS NMR spectra, BTMA+ ions were not present in cages of the obtained zeolites, but TMA+ ions existed instead. It means that BTMAOH underwent degradation during the conversion. Moreover, the effects of Si/Al ratio of starting FAU zeolite, synthesis parameters (BTMAOH/SiO2 and H2O/SiO2 ratios) and the addition of alkali metal chlorides on the hydrothermal conversion of FAU zeolite into MTN zeolite are discussed. As compared to amorphous SiO2/γ-Al2O3, which produced impurity, the hydrothermal conversion of FAU zeolite showed a fast crystallization rate and a high selectivity to MTN zeolite formation. These phenomena indicate that the assembly of locally ordered aluminosilicate species coming from the decomposition or dissolution of FAU zeolite should be taking part in the conversion process.

Effect of addition of alkali metal salts in hydrothermal synthesis and post heat-treatment on porosity of SBA-15

SBA-15 was hydrothermally synthesized at 80 °C for 48 h, and then the surfactant template for mesopore formation was removed by extraction with ethanol, washing with nitric acid, and heating at 200 °C. Addition of alkali metal chlorides to a synthesis gel of SBA-15 increased its mesopore diameter in the following order: no added salt < LiCl < KCl < CsCl. The micropore volume did not change with the addition of any alkali metal and was around 0.17 mL g–1. These results suggest that alkali metal salt is inside the mesopore with a micelle template. When a small amount of potassium chloride was impregnated in SBA-15 after extraction and washing, micropore volume reduced almost to zero with heating at 400 °C in dry air, and the mesopore diameter and pore wall thickness were reduced by a larger amount than for non-impregnated SBA-15. It is likely that the micropores in the mesopore wall vanish due to condensation of silanols and/or reconstruction of siloxane bonds on the micropore wall, which are catalyzed by alkali metal halides.

Effects of Lewis acid-type transition metal chloride additives on the thermal degradation of ABS

The thermal degradation of ABS in the presence of Lewis acid-type transition metal chloride additives has been studied by thermogravimetric analysis. The reaction of transition metal chlorides (NiCl 2, CoCl 2, ZnCl 2 and FeCl 3) and ABS has been found to occur during the thermal degradation of ABS. In an inert atmosphere, char formation is observed, and some 10–30% of the reaction product is non-volatile at 600 °C. From model studies, it was found that the interaction of transition metal chloride and the acrylonitrile moieties of ABS at elevated temperatures leads to crosslinking of the polymer. The resulting enhancement of char formation in an inert atmosphere has been explained as a catalytic crosslinking effect of transition metal chloride compounds via a macroradical coupling mechanism. Although this crosslinking does not increase the threshold temperature for decomposition of ABS, it decreases the formation of flammable small molecules. On the other hand, transition metal chloride catalysed char formation of ABS in air was unsuccessful due to the oxidative degradation of the char at a higher temperature.