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Sulfur tolerance properties of rhodium phosphide (Rh2P) were qualitatively and quantitatively evaluated by the temperature-programmed sulfidation (TPS) technique. The TPS profile of the Rh/SiO2 catalyst demonstrated a peak attributed to Rh2S3 formation around 400 degrees C. The TPS profiles of P-added Rh (Rh-P) catalysts showed this peak shifted to higher temperatures and lower intensity with higher P/Rh ratio or reduction temperature. Quantitative analysis of TPS profiles revealed that the amount of reacted H2S was remarkably lower (about 80 %) with P/Rh ratio more than 1.5, compared with Rh catalyst. The amount of reacted H2S decreased with greater intensity of the Rh2P peak in the XRD pattern, indicating that Rh2P has high sulfur tolerance. Furthermore, the relationship between P/Rh ratio and S/Rh ratio (calculated from TPS profile) of Rh-P catalysts agreed with the reported S/Rh value, showing the TPS method has high validity for qualitative analysis. We conclude that the TPS technique is a superior method for evaluation of sulfur tolerance for phosphide catalysts, and Rh2P has remarkably high sulfur tolerance compared with Rh catalyst.

Effect of P/Rh ratio and reduction temperature on catalytic activity and product selectivity of rhodium phosphide (Rh2P) for hydrodeoxygenation (HDO) of phenol was studied to develop production of ...

We report a synthesis strategy for pure hydroxyapatite (HAp) using an amorphous calcium carbonate (ACC) colloid as the starting source. Room-temperature phosphorylation and subsequent calcination produce pure HAp via intermediate amorphous calcium phosphate (ACP). The pre-calcined sample undergoes a competitive transformation from ACC to ACP and crystalline calcium carbonate. The water content, ACC concentration, Ca/P molar ratio, and pH during the phosphorylation reaction play crucial roles in the final phase of the crystalline phosphate compound. Pure HAp is formed after ACP is transformed from ACC at a low concentration (1 wt%) of ACC colloid (1.71

The structure and performance of TiO2-supported Re (Re/TiO2) catalysts for selective hydrogenation of carboxylic acid derivatives have been investigated. Re/TiO2 promotes selective hydrogenation reactions of carboxylic acids and esters that form the corresponding alcohols, and of amides that generate the corresponding amines. These processes are not accompanied by reduction of aromatic moieties. A Re loading amount of 5 wt% and a catalyst pretreatment with H2 at 500 °C were identified as being optimal to obtain the highest catalytic activity for the hydrogenation processes. The results of studies using various characterization methods, including X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM), indicate that the Re species responsible for the catalytic hydrogenation processes have sub-nanometer to a few nanometer sizes and average oxidation states higher than 0 and below +4. The presence of either a carboxylic acid and/or its corresponding alcohol is critical for preventing the Re/TiO2 catalyst from promoting production of dearomatized byproducts. Although Re/TiO2 is intrinsically capable of hydrogenating aromatic rings, carboxylic acids, alcohols, amides, and amines strongly adsorb on the Re species, which leads to suppression of this process. Moreover, the developed catalytic system was applied to selective hydrogenation of triglycerides that form the corresponding alcohols.

Previous studies on cadmium adsorption of calcium carbonate have found that polymorph, and, crystallinity are influential factors for adsorbing cadmium ions. The predominant factor for cadmium adsorption has yet to be elucidated because these factors are linked. To overcome this, here each factor is investigated separately. First, atmospheric grinding prepared surf clam (aragonite phase) and scallop (calcite phase) shells with similar crystallite sizes and specific surface areas. Using adsorption isotherm models, kinetics, X-ray diffraction analysis, and TEM observations, both calcite and aragonite react with cadmium to form cadmium carbonate. The chemisorption follows the adsorption mechanism reported in the literature. Based on the Langmuir isotherm model fitting, the maximum adsorbed amount for the ground surf clam shells is 633.3 mg/g, while that for scallop shells is 195.8 mg/g. Then fine surf clam shell particles with a similar specific surface area, and with a relatively wide range of the aragonite ratio, and crystallite size are prepared via a combination of grinding and a subsequent calcination process. Our experiments where one explanatory variable is changed at a time demonstrate that the polymorph ratio and crystallite size of the ground shells play key roles in the chemisorption.

In this study, the low-temperature synthesis of rhodium phosphide (Rh2P) on alumina (Al2O3) using triphenylphosphine (TPP) as a phosphorus (P) source and its catalytic activity toward hydrodesulfurization (HDS) were investigated to prepare a highly active HDS catalyst. TPP was more easily reduced than phosphate, and Rh2P was formed in the P(T)/Rh/Al2O3 catalyst prepared from TTP at lower temperature as compared with the temperature required by Rh-P(A)/Al2O3 catalyst prepared from a phosphate precursor. However, after reduction at a low temperature (450 °C), excess P covered the surface of Rh2P. The optimal reduction temperature for HDS rate of the P(T)/Rh/Al2O3 catalyst (650 °C) was lower than that of the Rh-P(A)/Al2O3 catalyst (800 °C). Furthermore, this temperature was slightly higher than the optimal reduction temperature for CO uptake (600 °C). These results are explained as follows: HDS rate is increased by both elimination of excess P on the active sites at higher reduction temperatures and enhancement of the crystallinity of Rh2P. Furthermore, because the particle size of the P(T)/Rh/Al2O3 catalyst (ca. 1.2 nm) was substantially smaller than that of the Rh-P(A)/Al2O3 catalyst, the P(T)/Rh/Al2O3 catalyst exhibited greater HDS rate compared with the Rh-P(A)/Al2O3 catalyst.

In this work, the development of a highly active noble metal phosphide (NMXPY)-based hydrodesulfurization (HDS) catalyst with a high hydrogenating ability for heavy oils was studied. NMXPY catalysts were obtained by reduction of P-added noble metals (NM-P, NM: Rh, Pd, Ru) supported on SiO2. The order of activities for the hydrogenation of biphenyl was Rh-P > NiMoS > Pd-P > Ru-P. This order was almost the same as that of the catalytic activities for the HDS of dibenzothiophene. In the HDS of 4,6-dimethyldibenzothiophene (4,6-DMDBT), the HDS activity of the Rh-P catalyst increased with increasing reaction temperature, but the maximum HDS activity for the NiMoS catalyst was observed at 270 °C. The Rh-P catalyst yielded fully hydrogenated products with high selectivity compared with the NiMoS catalyst. Furthermore, XRD analysis of the spent Rh-P catalysts revealed that the Rh2P phase possessed high sulfur tolerance and resistance to sintering.

Metal phosphide has been widely investigated as a hydrotreating catalyst. The preparation and performance of noble metal phosphide catalyst was examined to develop new phosphide hydrotreating catalysts. The supports affect reducibility of phosphate as a P precursor. Since phosphate does not strongly interact with SiO2 and TiO2 supports, Rh2P was easily formed on these supports. Furthermore, formation of Rh2P enhanced the hydrodesulfurization (HDS) activity of supported Rh–P catalyst. The type of noble metal (NM) and P/NM ratio also strongly affect formation of noble metal phosphide and HDS activity. Excess P facilitates formation of noble metal phosphides at lower reduction temperature. In contrast, excess P causes the aggregation of noble metal phosphide and formation of phosphorus rich noble metal phosphide. Rh–1.5P/SiO2 catalyst had high and stable activity for HDS reaction. Furthermore, this catalyst showed significantly higher hydrodenitrogenation (HDN) activity than sulfided NiMoP/Al2O3 catalyst. Therefore, Rh2P has great potential as a new hydrotreating catalyst.

Effect of sodium (Na) addition on rhodium phosphide (Rh2P) formation on MFI zeolite, SiO2 and Al2O3 and hydrodesulfurization (HDS) activity were examined. The TPR results revealed that Na addition enhanced reducibility of phosphates. The XRD results indicated that Rh2P phase was easily formed on NaMFI support as compared with on HMFI support. The maximum HDS activity of Rh–P/NaMFI catalyst was obtained at lower reduction temperature and this activity was higher than that of Rh–P/HMFI catalyst. We concluded that since Na would weaken interaction between Al and phosphate, high HDS activity of Rh–P/NaMFI catalyst was observed at lower reduction temperature.

Effects of reduction temperature and phosphorus loading on rhodium phosphide (Rh 2 P) formation and on the catalytic activity of Rh- x P catalysts for hydrodesulfurization (HDS) were investigated to prepare highly active HDS catalysts. Analysis of the Rh- x P catalysts showed that a suitable P loading for HDS activity is 1.5 wt%—four times greater than that of an Rh catalyst. Temperature-programmed reduction and X-ray diffraction analyses of the Rh- x P catalysts showed that Rh 2 P is readily formed in catalysts with higher P loading. In contrast, the results of transmission electron microscopy observation and CO adsorption experiments indicated that the Rh 2 P particle size increased with increasing P content. Thus, the high HDS activity of the Rh-1.5P catalyst was explained by the formation of small Rh 2 P at a relatively low reduction temperature (550 °C).

リン化ロジウム（Rh2P）触媒の活性点形成とその水素化脱硫（HDS）活性に対する担体の影響について検討した。担体には金属酸化物（MOx: SiO2，Al2O3，TiO2，MgOおよびZrO2）を用いた。いずれの担体の場合でも担持ロジウム－リン（Rh–P）触媒を水素還元するとRh2Pが生成した。一方，Rh2Pの生成温度は担体により異なった。このRh–P触媒のHDS活性は還元温度によって大きく変化した。最適な温度で還元したRh–P/MOx触媒のHDS活性の序列はSiO2～TiO2～Al2O3＞MgO＞ZrO2となった。また，還元温度を上昇させるとRh–P/MOx触媒のTOFは増加し，これはRh2Pが生成したためであることが分かった。Rh–P/MOx触媒のTOFの序列はTiO2＞ZrO2＞Al2O3＞SiO2＞MgOとなり，これはチオフェン転化率の序列とは一致しなかった。Rh–P/TiO2触媒が高いTOFを示した原因としては，部分的に硫化されたTiO2の生成が挙げられる。一方，Rh–P/MgO触媒のTOFが低かったのは，MgOは塩基性担体であり耐硫黄性が低かったためと考えられる。

A novel, green method for hydrogen (H2) production was studied; the method involves the mechanical mixing of aluminum (Al) with water (H2O). We examined the use of glass and stainless steel reactors. When the glass reactor was used, the induction period of the reaction of Al with H2O was long. The induction period decreased remarkably upon increasing the revolution rate; the optimal revolution rate was 1250 rpm. Furthermore, the reaction of Al with H2O in the stainless steel reactor was examined to investigate the practical feasibility of this H2 production method. In this case too an induction period was observed, and the induction period decreased upon increasing the reaction temperature and Al weight.

Preparation of noble metal (NM) (Rh, Pd, Ru, Pt) phosphide species and their catalytic activities for hydrodesulfurization (HDS) of thiophene were investigated. Noble metal phosphides (NMXPY) catalysts were prepared by reduction of P-added NM (NM-P) supported on silica (SiO_2) with hydrogen. Hydrogen consumption peaks at around 350–700 °C, which were attributed to the formation of NMXPY, were observed in temperature-programmed reduction (TPR) spectra of all NM-P/SiO_2. Furthermore, X-ray diffraction (XRD) patterns of NM-P/SiO_2 indicate that NMXPY (Rh_2P, Pd_P, Ru_2P, PtP_2) were formed by hydrogen reduction at high temperature. The reduction temperature strongly affected HDS activities of NM-P/SiO_2 catalysts. The NM-P/SiO_2 catalysts, other than Pt, showed higher HDS activities than NM/SiO_2 catalysts. The HDS activity of the Rh-P/SiO_2 catalyst was the highest among those of NM-P/SiO2 catalysts. This activity was higher than that of the Ni-P catalyst and was the same as that of pre-sulfided CoMoP/Al_2O_3 catalyst. Furthermore, the Rh-P/SiO_2 catalyst showed stable activity even after reaction for 30 h. The XRD, transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS) results revealed that the formation of small Rh_2P particles and suitable P addition to form Rh_2P caused the high HDS activity of the Rh-P catalyst.

The catalytic activities of various noble metals (Pt, Pd, Rh, and Ru) supported on siliceous SBA-15 and Al-containing SBA-15 (AlSBA-15) for hydrodesulfurization (HDS) of thiophene at 350 °C were investigated. AlSBA-15 was prepared by a grafting method using aluminum isopropoxide (Al(OC3H7)3) hexane solution. The HDS activity of Pt/AlSBA-15 catalyst was the highest among those of various supported noble metal catalysts, and this activity was higher than that of commercial CoMo/Al2O3 HDS catalyst. The catalysts were characterized by XRD analysis, hydrogen adsorption, 2-propanol dehydration, cumene cracking, and FT-IR. Dispersion of Pt on SBA-15 was remarkably enhanced by Al grafting. It was revealed that the acidity of AlSBA-15 was higher than that of SBA-15. Furthermore, Bronsted acid sites were observed on AlSBA-15. FT-IR spectra of thiophene adsorbed on AlSBA-15 indicate that thiophene molecules interact with Bronsted acid sites on the surface of AlSBA-15 and that the strength of this interaction was stronger than that of SBA-15. Based on these results, thiophene molecules activated on Bronsted acid site of AlSBA-15 and hydrogen molecules activate to form spillover hydrogen on Pt particles in Pt/AlSBA-15 catalyst in the HDS of thiophene.

Hydrodesulfurization (HDS) of thiophene over silica-modified alumina-supported platinum (Pt/SiO_2-Al_2O_3) catalysts was examined. The HDS activity of a Pt/Al_2O_3 catalyst was enhanced by silica modification. However, the optimal silica loading for HDS activity could not be identified. The dispersion of platinum on alumina, as measured by the hydrogen adsorption method, was enhanced by silica modification and the optimal silica loading for platinum dispersion was 10 to 40 wt%. The acidity of SiO_2-Al_2O_3 was evaluated by 2-propanol dehydration (200°C) and cumene cracking (400°C). The optimal silica loading for the acidity of SiO_2-Al_2O_3 was 90 wt%. Furthermore, the presence of Brönsted acid sites on SiO_2-Al_2O_3 was confirmed by a pyridine adsorption method with FT-IR spectroscopy. The high HDS activity of the Pt/SiO_2-Al_2O_3 catalyst is caused by both high Pt dispersion and formation of Brönsted acid sites.

The catalytic activities and properties of platinum supported on siliceous MCM-41 and Al-modified MCM-41, such as Al-incorporated MCM-41 (AlMCM-41) and alumina-modified MCM-41 (Al 2 O 3 -MCM-41), for the hydrodesulfurization (HDS) of thiophene were investigated. Al 2 O 3 -MCM-41 was prepared by an impregnation method using aluminum nitrate (Al(NO 3 ) 3 ·9H 2 O) aqueous solution. Pt/Al 2 O 3 -MCM-41 catalyst showed high and stable activity for HDS of thiophene and this activity was remarkably higher than that of a commercial CoMo/Al 2 O 3 HDS catalyst. The catalysts were characterized by XRD, hydrogen adsorption, ammonia-TPD, 2-propanol dehydration, cumene cracking and FT-IR. Dispersion of platinum on Al 2 O 3 -MCM-41 was remarkably higher than on MCM-41 or on AlMCM-41. It was revealed that the acidity of Al 2 O 3 -MCM-41 was higher than that of MCM-41 or of AlMCM-41. Furthermore, it was observed that there exist Bronsted acid sites on Al-modified MCM-41. FT-IR spectra of thiophene adsorbed on Al-modified MCM-41 support indicates that thiophene molecules interact with Bronsted acid sites on Al-modified MCM-41. It was found that the HDS activity of Pt/quartz mixed mechanically with Al-modified MCM-41 catalyst was higher than that calculated. This suggests that there exists spillover hydrogen on supported Pt catalysts in the HDS of thiophene. Results revealed that the high activity of Pt/Al 2 O 3 -MCM-41 catalyst for HDS reaction is due to good harmony of high dispersion of Pt particles and Bronsted acidity of the support.

The catalytic activities and properties of noble metals (Pt, Pd, Rh, Ru) supported on silica gel (SiO 2 ) and alumina-modified silica gel (Al 2 O 3 -SiO 2 ) were investigated for the hydrodesulfurization of thiophene. Al 2 O 3 -SiO 2 was prepared by an impregnation method using aluminum nitrate (Al(NO 3 ) 3 · 9H 2 O) aqueous solution. Pt/ 8 wt%Al 2 O 3 -SiO 2 catalyst showed the highest activity for hydrodesulfurization of thiophene among various supported noble metal catalysts and this activity was higher than that of commercial CoMo/Al 2 O 3 hydrodesulfurization catalyst. The sulfur tolerance of noble metal/SiO 2 was enhanced by Al 2 O 3 modification of SiO 2 and Pt/8 wt%Al 2 O 3 -SiO 2 catalyst showed the highest sulfur tolerance among the supported noble metal catalysts. Pt/ 8 wt%Al 2 O 3 -SiO 2 catalyst had high hydrogenating ability for unsaturated C 4 hydrocarbons formed in the hydrodesulfurization of thiophene. The catalysts were characterized by 2-propanol dehydration, cumene cracking, XRD, H 2 adsorption and FT-IR. Dispersion of Pt on 8 wt%Al 2 O 3 -SiO 2 was remarkably higher than that on SiO 2 and the particle size of Pt on 8 wt%Al 2 O 3 -SiO 2 was the lowest among the supported noble metal catalysts. The acidity of 8 wt%Al 2 O 3 -SiO 2 was higher than that of SiO 2 . Furthermore, Bronsted acid sites were present on 8 wt%Al 2 O 3 -SiO 2 . FT-IR spectroscopy of thiophene adsorbed on 8 wt%Al 2 O 3 -SiO 2 support indicated that the thiophene molecule interacts with the Bronsted acid site on 8 wt%Al 2 O 3 -SiO 2 . The activity of the double-layer (Pt/SiO 2 + 8 wt%Al 2 O 3 -SiO 2 ) catalyst obtained experimentally was higher than that calculated. This suggests that spillover hydrogen was present on Pt/Al 2 O 3 -SiO 2 in the hydrodesulfurization of thiophene. Both the Bronsted acid sites of Al 2 O 3 -SiO 2 and the Pt particles in the Pt/Al 2 O 3 -SiO 2 catalyst act as active sites for the hydrodesulfurization of thiophene.

Pt/4wt%Al2O3-MCM-41 catalyst showed high and stable activity for hydrodesulfurization of thiophene at 350°C and this activity was higher than that of commercial CoMo/Al2O3 hydrodesulfurization catalyst. Pt/4wt%Al2O3-MCM-41 catalyst has high hydrogenating ability in the hydrodesulfurization of thiophene. The Bronsted acid sites of Al2O3-MCM-41 and the spillover hydrogen formed on Pt particle in Pt/Al2O3-MCM-41 catalyst play an important role for the hydrodesulfurization of thiophene.

The Pt/AlSBA-15 catalyst showed high and stable catalytic activity for the hydrodesulfurization of thiophene at 350°C and this activity was higher than those of Pt/SBA-15 and commercial CoMo/Al2O3 catalysts. The Pt/AlSBA-15 catalyst has high sulfur-tolerant property toward hydrogen sulfide formed in hydrodesulfurization of thiophene. The Broensted acid sites of AlSBA-15 and the spillover hydrogen formed on Pt particle in Pt/AlSBA-15 catalyst play an important roles for the hydrodesulfurization of thiophene.

Catalytic degradation of low density polyethylene (LDPE) including small amounts of poly(vinyl chloride) (PVC) has been carried out to develop a chlorine tolerant catalyst for chemical recycling of waste plastics. H-galloaluminosilicate has been found to be highly active as a catalyst for converting LDPE into aromatic hydrocarbons in the presence of hydrogen chloride.