A preliminary evaluation on the use of the cyclam functionalized resin for the noble metals sorption

A new resin has been prepared through a reaction between the vinylbenzyl chloride–divinylbenzene copolymer and the 1,4,8,11-tetraazacyclotetradecane (cyclam). This resin has been investigated after the characterization of the FTIR, batch and the dynamic sorption behavior of Au(III), Pt(IV) and Pd(II) ions took place. The sorption has been optimized with respect to HCl solutions. The maximum sorption properties were achieved from the solution of 0.1 M HCl. The sorption of Au(III), Pt(IV) and Pd(II) ions during a dynamic procedure in the presence of the 20-fold excess metals i.e. Cu, Fe, Ni resulted in an outcome of up to 400 mg of noble metals per gram of dry resin. The study of the noble metal loading was carried out over a wide range of the HCl concentration and in media of various multicomponent solutions of common metals.     

Fluorine concentration of coals in China—An estimation considering coal reserves

Representative coal fluorine concentrations are essential to better estimate the environmental and health effects associated with the fluorine emissions from coal utilization. The average fluorine concentrations of coals in China are estimated based on fluorine analyses of about 2000 coal samples and coal reserves tonnage. The results reveal that the estimated average weighted fluorine concentrations of Carboniferous and Early Permian (C–P₁), Late Permian (P₂), Late Triassic (T₃), Early and Middle Jurassic (J_1-2), Late Jurassic and Early Cretaceous (J₃–K₁), and Eogene and Neogene (E–N) coals are 149.4, 200.9, 84.1, 84.46, 134.2, and 352.8 μg/g, respectively. The overall average weighted fluorine concentration of coals in China is 130 μg/g and is approximately one third higher than the reported value of the US coals.     

Combination of flame synthesis and high-throughput experimentation: The preparation of alumina-supported noble metal particles and their application in the partial oxidation of methane

Mono and multi-noble metal particles on Al₂O₃ were prepared in one step by flame spray pyrolysis (FSP) of the corresponding noble metal precursors dissolved in methanol and acetic acid (v/v 1:1) or xylene. The noble metal loading of the catalysts was close to the theoretical composition as determined by WD-XRF and LA-ICP-MS. The preparation method was combined with high-throughput testing using an experimental setup consisting of eight parallel fixed-bed reactors. Samples containing 0.1–5 wt% noble metals (Ru, Rh, Pt, Pd) on Al₂O₃ were tested in the catalytic partial oxidation of methane. The ignition of the reaction towards carbon monoxide and hydrogen depended on the loading and the noble metal constituents. The selectivity of these noble metal catalysts towards CO and H₂ was similar under the conditions used (methane: oxygen ratio 2:1, temperature from 300 to 500 °C) and exceeded significantly those of gold and silver containing catalysts.Selected catalysts were further analysed using XPS, BET, STEM-EDXS and XANES/EXAFS. The catalysts exhibited generally a specific surface area of more than 100 m²/g, and were made up of ca. 10 nm alumina particles on which the smaller noble metal particles (1–2 nm, partially oxidized state) were discernible. XPS investigation revealed an enrichment of noble metals on the alumina surface of all samples. The question of alloy formation was addressed by STEM-EDXS and EXAFS analysis. In some cases, particularly for Pt–Pd and Pt–Rh, alloying close to the bulk alloys was found, in contrast to Pt–Ru being only partially alloyed. In situ X-ray absorption spectroscopy on selected samples was used to gain insight into the oxidation state during ignition and extinction of the catalytic partial oxidation of methane to hydrogen and carbon monoxide.     

Fabrication of self-binding noble metal/flexible graphene composite paper

Self-binding noble metal (Pt, Au, and Ag)/graphene composite papers as large as 13 cm in diameter were fabricated using a flow-directed method where in situ reduced graphene served as a “binder”. The papers were characterized by X-ray diffraction, scanning and transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. This approach yielded well dispersed metals with various nanostructures both on and between the graphene layers to form papers with good conductivity and flexiblility. The 300 °C-annealed Ag/graphene papers were evaluated as binder-free anodes for lithium ion batteries, delivering a reversible charge capacity of 689 mAh/g at a current density of 20 mA/g.     

The effect of TiO2 particle size on the characteristics of Au–Pd/TiO2 catalysts

The nanocrystalline TiO₂ materials with average crystallite sizes of 9 and 15 nm were synthesized by the solvothermal method and employed as the supports for preparation of bimetallic Au/Pd/TiO₂ catalysts. The average size of Au–Pd alloy particles increased slightly from sub-nano (< 1 nm) to 2–3 nm with increasing TiO₂ crystallite size from 9 to 15 nm. The catalyst performances were evaluated in the liquid-phase selective hydrogenation of 1-heptyne under mild reaction conditions (H₂ 1 bar, 30 °C). The exertion of electronic modification of Pd by Au–Pd alloy formation depended on the TiO₂ crystallite size in which it was more pronounced for Au/Pd on the larger TiO₂ (15 nm) than on the smaller one (9 nm), resulting in higher hydrogenation activity and lower selectivity to 1-heptene on the former catalyst.     

Preparation of noble metal nanocatalysts and their applications in catalytic partial oxidation of methane

A series of noble metal catalysts (Ru, Rh, Ir, Pt, and Pd) supported on alumina-stabilized magnesia were prepared and employed in partial oxidation of methane. The prepared catalysts were characterized using BET, SEM, TEM and H₂S chemisorption techniques. The results revealed that the Ru and Rh catalysts had the highest activity in catalytic partial oxidation of methane. Based on the obtained results the following order of activity was observed for different catalysts in partial oxidation of methane: Rh ～ Ru > Ir > Pt > Pd. The obtained results also showed a high catalytic stability without any decrease in methane conversion up to 50 h of reaction.     

Microwave-assisted hydroconversions of demineralized coal liquefaction residues from Shenfu and Shengli coals

Microwave-assisted hydroconversions of demineralized coal liquefaction residues (DCLRs) from Shenfu (SF) and Shengli coals were investigated using methanol or ethanol as the solvent for both reaction and extraction. The results show that the solubilities of hydroconverted DCLRs in methanol under 0.7 MPa of initial hydrogen pressure (IHP) follow the order: non-catalytic hydroconversion = activated carbon-catalyzed hydroconversion < Pd/C-catalyzed hydroconversion < Ni-catalyzed hydroconversion; the solubility of Ni-catalyzed hydroconverted DCLR from SF coal in methanol increases with raising temperature up to 140 °C and with increase in IHP; the solubility of Ni-catalyzed hydroconverted DCLR from SF coal in methanol under 0.7 MPa of IHP at 130 °C is higher than that in ethanol. The molecular compositions of the extractable fractions were analyzed with GC/MS and the structural features of some extractable and inextractable fractions were characterized with FTIR.     

Elucidation of hydrogen mobility in coal under reductive atmosphere using a tritium tracer method

Hydrogen exchange reaction of three Argonne coals (Illinois No. 6, Upper Freeport and Pocahontas #3) and Wandoan coal with tritiated gaseous hydrogen were performed at several temperatures. Hydrogen exchange reaction was performed in a flow reactor packed with 0.4 g of coal and 0.05 g of catalysts under the following conditions: pressure 15 kg/cm², temperature 200, 250, 300 °C, carrier gas H₂ or N₂ 5 ml/min. When a pulse of [³H]H₂ was introduced into a coal in H₂ carrier gas at several temperatures, the delay of [³H]H₂ pulse observed increased with increasing the reaction temperature and decreased with increasing coal rank. Further in the reaction of tritiated coals with gaseous hydrogen at constant temperature, the hydrogen exchange rate was estimated from the release rate of [³H]H₂. The apparent hydrogen exchange rate at 200 °C was higher than that at 250 °C. This shows that the hydrogen with low reactivity came to participate in the reaction at high temperature. When the reaction of tritiated coal with gaseous hydrogen was performed during heat treatment, one, two or three peaks of tritium concentration were observed in the outlet of the reactor depending on temperature (200, 250 or 300 °C, respectively) at which tritium was incorporated into coal initially. It was suggested that there were at least three kinds of hydrogen with different reactivity in coal.     

Ir promotion of TiO2 supported Au catalysts for selective hydrogenation of cinnamaldehyde

We synthesized Ir-on-Au (Au–Ir) nanoparticles (NPs) using 8–9 nm Au NPs, which had a partial coverage of Ir. Both the studied systems allowed the obtainment of cinnamyl alcohol with high selectivities (> 83%). However, Au–Ir/TiO₂ delivered a hydrogenation rate 5 times higher than that of Au/TiO₂. The deposition of Ir onto the surface of Au and the presence of surface Au–Ir alloy were confirmed by UV–vis and HRTEM respectively. Moreover. Moreover, the strongly shifted XPS binding energy implyed the electron transfer from Ir to Au, which was believed to be responsible for the enhanced H₂ activation capacity of Au.     

Assessment of the water quality produced from mechanical thermal expression processing of three Latrobe Valley lignites

Mechanical Thermal Expression (MTE) is a developing non-evaporative brown coal (lignite) dewatering technology. This study assesses the physical and chemical properties of MTE product water expressed from three Latrobe Valley lignites. MTE product water was found to be acidic, contain concentrations of dissolved organic and inorganic components of up to 5.3 g/L and was found to contain suspended colloidal coal particles of up to 1.7 g/L. The concentration of contaminants in the product water was found to be related to different coal types. The selection of coals for future MTE processing will have significant implications for the quality of water produced. Many investigated water parameters are in breach of selected water use guidelines and remediation of the water from this process is required prior to reuse or disposal.     

Carbon nanotube and nanofiber syntheses by the decomposition of methane on group 8–10 metal-loaded MgO catalysts

We have found that several precious metal-loaded MgO catalysts are active in the formation of carbon nanotube (CNT) by the chemical vapor deposition (CVD) of methane. The catalysts were prepared with nine metals (Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt) by impregnation onto a high surface area MgO. CNT synthesis was carried out in the temperature range from 600 °C to 1000 °C after reduction with H₂ at 800 °C.The amount of carbon deposited and crystallinity in the produced CNT on nine metals showed interesting tendencies: (i) The amount of carbon formed increased in the following transition series metals: first < second < third row transition elements, and (ii) the index of crystallinity I_G/I_D in Raman-bands of the CNTs decreased in the following order: 8 > 9 > 10 in the Periodic Table. Group 8 and 9 metals produced tube type fibers composed of the graphite layers arranged parallel to the fiber axis. On the other hand, carbon nanofibers (CNFs) grown on group 10 metals had herringbone type graphene sheets.     

The effect of extraction condition on ‘HyperCoal’ production (1)—under room-temperature filtration

In order to produce ashless coal (HyperCoal) in a high yield, extractions with several organic solvents—tetralin, 1-methylnaphthalene, dimethylnaphthalene and light cycle oil (LCO) at 200–380 °C were conducted for various ranks of coals, and subsequent solid/solution separation was done at room temperature. LCO was found to be a useful, cost-effective solvent, since it gave similar extraction yields to three other reagent solvents. The extraction yield for Illinois No. 6 coal gradually increased over 200 °C, and a significant increase in extraction yield was observed from 350 to 360 °C. We succeeded in producing ashless coal with less than 0.1% in ash content for seven of nine coals used in this study.     

Ultra-selective gas phase catalytic hydrogenation of aromatic nitro compounds over Au/Al2O3

We report, for the first time, the exclusive (and time invariant) gas phase hydrogenation of p-chloronitrobenzene to p-chloroaniline over Au/Al₂O₃ where 393 K ⩽ T ⩽ 523 K (ΔE_a = 49 kJ mol⁻¹). Under the same conditions, Pd/Al₂O₃ promoted the formation of nitrobenzene and aniline, i.e. composite hydrodechlorination and hydrogenation. Reaction over Au–Pd/Al₂O₃ delivered equivalent activity/selectivity to that obtained with Pd/Al₂O₃. Temperature programmed reduction analysis and hydrogen uptake measurements suggest there is negligible Au–Pd interaction in the bimetallic. Exclusive formation of the corresponding haloaniline is also demonstrated over Au/Al₂O₃ for a series of mono- and di-substituted halonitroarenes; the activity sequence is consistent with electron withdrawing substituent activation.     

Mutagenicity of eluent by hot water extraction of various coals: Effect of chlorination

Six kinds of powdery coals (two bituminous coals, two sub-bituminous coals, and two lignites) were extracted by hot water, and the eluents obtained were analyzed for total organic carbon (TOC), absorbance at 260 nm (A₂₆₀), and pH. The TOC in the eluents decreased in the order, lignites > sub-bituminous coals > bituminous coals. The eluents of lignite gave high A₂₆₀/TOC values and fairly low pH compared to other coals. Chemical structure of the organic matter eluted from coals was discussed with the aid of FTIR analysis. The coal eluents were analyzed by the Ames mutagenicity assay using Salmonella typhimurium TA100 and TA98 strains, and no mutagenicity was observed for all of the six coals. However, especially for the lignites, chlorination of the eluents produced an appreciable mutagenicity, and the expression of mutagenicity was dependent upon the type of coal. The mutagenicity was extinguished when metabolic activation (rat liver homogenate, +S9) was applied.     

Selective aerobic oxidation of alcohols over Au–Pd/sodium titanate nanotubes

The catalytic application of Au–Pd nanoparticles supported on sodium titanate nanotubes (NaTNTs) for liquid-phase aerobic oxidation of alcohols is reported, for the first time. This reaction occurs at 80–120 °C, 1 atm and solvent-/alkali-free conditions yielding the corresponding carbonyls in high selectivity. This catalyst was reusable and found to be more active/selective than the corresponding monometallic Au and Pd catalysts and Au–Pd/TiO₂. Higher dispersion, smaller particle size and higher amount of electron density at gold are the causes for the superior activity of Au–Pd/NaTNT catalyst.     

Joining of Cf/SiC composite with a Cu–Au–Pd–V brazing filler and interfacial reactions

A new Cu–Au–Pd–V filler alloy was designed for the joining of C_f/SiC composite. Its wettability on the composite was studied with the sessile drop method. After heating at 1473 K for 10 min the filler alloy showed a low contact angle of 5°. The interfacial reactions under the brazing condition of 1443 K/10 min resulted in the formation of VC_0.75 reaction band at the surface of the composite, and the microstructure in the central part of the joint is composed of Cu(Au, Pd) solid solution and Pd₂Si compound. The average three-point bend strength of the C_f/SiC–C_f/SiC joints at room temperature is 135 MPa. The joints also exhibit stable strengths at high temperatures of 873–1073 K. The presence of refractory Pd₂Si compound within the Cu(Au, Pd) solid solution matrix throughout the joint should contribute to the stable high-temperature property.     

Characterization of Pd impregnated on metal/silica-pillared H-keyaites (M-SPK,M = Ti,Zr) catalysts for partial oxidation of methane to hydrogen

Pd(5) impregnated metal/silica-pillared H-keyaites (M-SPK, M = Ti, Zr) catalysts were prepared for the partial oxidation of methane (POM) to hydrogen. The catalysts were characterized by BET, TEM, SAXS and XPS. In addition, the catalytic yield of the POM to hydrogen over Pd(5) impregnated on M-SPK and Pd(5)/Al₂O₃, commercial catalyst were investigated in a fixed bed flow reactor under (Ed atmosphere. BET-specific surface areas, average pore sizes and nitrogen adsorption/desorption isotherms were 284.3–396.2 m²/g, 3.3–3.8 nm and type B on type IV isotherms for Pd(5)/M-SPK(M = Ti, Zr), and 90.5 m²/g, 8.3 nm and type E on type IV isotherm for Pd(5)/Al₂O₃, respectively. TEM images of SPK and Pd(5)/SPK showed the formation of mesoporous layer compounds, as well as the homogenous dispersion of Pd particles on the surface. SAXS peaks at 0.13 Å for fresh Pd(5)/SPK were maintained without being broken, even after about 53 h in stream at 973 K. XPS showed the existence of two oxidation states for Pd (Pd⁰ and Pd²⁺) on the surface of the catalyst, depending on the carrier, whereas the presence of Ti and Zr in SPK induced a change in the oxidation state (O²⁻, O⁻) of the catalyst. The yield values of the POM to hydrogen over Pd(5)/M-SPK(M = Ti, Zr) were 64.9% and 55.8%, respectively, at 973K, CH₄/O₂ = 2, GHSV = 8.4 × 10⁴ ml/g_cat h, and these values were kept constant even after 70 h in stream. These results confirm that Ti and Zr in SPK frame induced oxidation states of Pd, and that the yield of Pd(5)/M-SPK positively regulates the POM to hydrogen.     

Hydrogen storage using heterocyclic compounds: The hydrogenation of 2-methylthiophene

Alkyl substituted thiophenes are promising candidates for hydrogen carriers, as their dehydrogenation reactions are known to occur under mild conditions. Four types of catalysts, including supported noble metals, bimetallic noble metals, transition metal phosphides and transition metal sulfides, have been investigated for 2-methylthiophene (2MT) hydrogenation and ring-opening. The major products were tetrahydro-2-methylthiophene (TH2MT), pentenes and pentane, with very little C₅-thiols observed. The selectivity towards the desired product TH2MT follows the order: noble metals > bimetallics > phosphides > sulfides. The best hydrogenation catalyst was 2% Pt/Al₂O₃ which exhibited relatively high reactivity and selectivity towards TH2MT at moderate temperatures. Temperature-programmed reaction (TPR) experiments revealed that pentanethiol became the major product, especially with HDS catalysts like CoMoS/Al₂O₃ and WP/SiO₂.     

Efficient and selective conversion of glycidol to 1,2-propanediol over Pd/C catalyst

The present work deals with the catalytic hydrogenolysis of glycidol to 1,2-propanediol. Reactions were carried out in a closed steel reactor using noble metal based heterogeneous catalysts (Pd, Rh, Pt) under hydrogen pressure (1–8 bars) in the temperature range of 25–140 °C. Pd/C shows the highest glycidol conversion (96%) under solvent free conditions after 24 h with high selectivity to 1,2-propanediol (93%). The effect of the solvent was also investigated and it was demonstrated that ethanol reduces drastically oligomer production enhancing selectivity up to 99% with a significant reaction time reduction (6 h). The Pd/C catalyst shows high recyclability and could be reused several times (9 cycles) without losses in activity and selectivity.     

Investigation on the combustion possibility of dry sewage sludge as a pulverized fuel of thermal power plant

Combustion possibility of three dry sludges as pulverized fuel of coal power plant like sub-bituminous Minco coal was studied by thermogravimetric analysis (TGA) and Drop Tube Furnace (DTF). TGA results showed that the fixed carbon contained with minor content in dry sludge was slowly burned than it of Minco coal. The linear regression for the Arrhenius plot to the experimental data is very good, and activation energies for overall combustion of Minco coal and DDSS are 64.382 and 26.799 kJ/mol, respectively. But, combustion patterns of KDSS and SDSS divided into devolatilization and oxidation reaction. It was derived that activation energies for the devolatilization of KDSS and SDSS are 27.127 and 12.571 kJ/mol in reciprocal proportion to volatile matter content, the fixed carbon combustion derives to 45.289 kJ/mol for KDSS, 33.777 kJ/mol for SDSS. Test results show that the volatile content in sludge significantly improved the combustion reactivity whereas the time for the combustion completion delayed. The conversion behavior of the coals and sludge observed in DTF was similar to that reflected in TGA. DTF studies showed that the individual sludge was lower conversion than the Minco coal, but the combustion of most sludge was completed at residence time of around 1 s, set temperature range of 1200 °C similar to commercial coal fired plant. These high IDT of sludge ashes with minimum 1214 °C are not expected to be associated with slagging and fouling in pulverized coal fired systems.