M. R. Goldwasser - Academia.edu (original) (raw)

Papers by M. R. Goldwasser

HAL (Le Centre pour la Communication Scientifique Directe), 2005

HAL (Le Centre pour la Communication Scientifique Directe), 2005

... Due to the high temperatures involved and the presence of steam, sinterization of the active ... more ... Due to the high temperatures involved and the presence of steam, sinterization of the active metal species and coke formation lead to catalysts deactivation and in some cases to plugging of the reactor [10]. ... catalyst stability; • coke formation by the following two reactions: ...

Studies in Surface Science and Catalysis, 2000

Resumen es: Se estudiaron una serie de precursores tipo perovskita (La 1-x Sr x CoO 3 con x = 0; ... more Resumen es: Se estudiaron una serie de precursores tipo perovskita (La 1-x Sr x CoO 3 con x = 0; 0,2; 0,4), preparados por el metodo de auto-combustion y caracteri...

Elsevier eBooks, 1993

Abstract A laterite iron mineral has been modified to obtain a K and Mn promoted laterite based c... more Abstract A laterite iron mineral has been modified to obtain a K and Mn promoted laterite based catalyst for CO hydrogenation reaction. Catalytic tests were conducted at atmospheric and higher pressure at 280–300 °C in fixed bed reactor systems. Characterization of the solids indicate a high influence of promotors on the Fe phases present on the catalysts. Mn inhibits formation of carbidic phases while the presence of K accelerates this effect. The double promoted laterite produces an active and stable solid with high selectivity to the C 2 -C 4 olefin fraction.

HAL (Le Centre pour la Communication Scientifique Directe), 2006

An investigation of the performances in Fischer-Tropsch reaction of 1wt% M/WC(X) (M = Co, Ru; X =... more An investigation of the performances in Fischer-Tropsch reaction of 1wt% M/WC(X) (M = Co, Ru; X = A, B), where A is a tungsten carbide protected by free carbon and B is a clean tungsten carbide, was carried out. Supported catalysts performances were compared to those of the parent tungsten carbides at 473 K and 20 bar. It was found that WC(A) produces mainly hydrocarbons but also 20-40% alcohols, whereas WC(B) activity is only towards linear alkanes. Before catalytic test, a reduction in pure hydrogen allows obtaining Co 0 and Ru 0 dispersed on layers of free carbon covering the WC core for the WC(A), and on a surface free of oxygen for WC(B). Co as Ru dispersions are improved on WC(B) compared to WC(A). A direct consequence is that Co/WC(B) has a better activity than Co/WC(A). Ru-W alloy formation could be responsible of the inobservance of a better activity for Ru/WC(B). On contrary, addition of Ru on WC(A) highly increases the activity and the production of heavy hydrocarbons. This beneficial effect, not observed with cobalt, could be attributed to a better dispersion of ruthenium on a carbon polymeric surface of WC.

Hyperfine Interactions, Dec 1, 1994

The syngas reaction has been studied using a laterite iron mineral, promoted with K and Mn. In si... more The syngas reaction has been studied using a laterite iron mineral, promoted with K and Mn. In situ activation under syngas, as well as pre-treatment with H2 followed by CO under mild and more severe conditions were tested. These activation procedures led to different iron phase compositions and to different catalytic selectivities. The C2-C4/CH4 ratio was significantly lower for those catalysts which after reaction showed the presence of hexagonal carbide and magnetite compared to the solid, which showed the highest proportion of Hagg carbide.

Journal of Catalysis, Jun 1, 1992

ABSTRACT

Applied Catalysis A-general, Oct 1, 1992

The effect of a deposit of 1 wt.-% vanadium on the physicochemical and catalytic properties of a ... more The effect of a deposit of 1 wt.-% vanadium on the physicochemical and catalytic properties of a USHY zeolite and of a FCC catalyst has been determined by various techniques: X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and methylcyclohexane transformation. With USHY and whatever the pretreatment: calcination under dry air flow at 546' C or hydrothermal treatment at 750' C, vanadium is well dispersed while in the FCC catalyst it is in the form of large aggregates (6 to 12 nm). The hydrothermal treatment causes a partial elimination of vanadium from the sample and a decrease of the surface concentration of vanadium. The matrix of the FCC catalyst limits the formation or/and the migration of the volatile vanadium species. Vanadium decreases the stability of the zeolite (decrease in crystallinity and increase of the deal~ination rate during the hydrothermal treatment) and consequently the activity of the zeolite and FCC catalyst samples. However this decrease in activity seems to be due partly to other phenomena, particularly to the exchange of the protonic sites by cationic vanadium species.

Se sintetizaron sólidos tipo espinelas modificados con sustitución parcial y completa de Al por G... more Se sintetizaron sólidos tipo espinelas modificados con sustitución parcial y completa de Al por Ga, y con sustitución parcial de Ni por metales nobles, mediante el método sol-gel de citrato. Las espinelas fueron utilizadas como soportes de catalizadores de Ni en diferentes proporciones (5, 10 y 15%). Los sólidos fueron caracterizados por técnicas tales como DRX, área específica BET y análisis termogravimétrico ATG. Se obtuvieron tamaños de partículas entre 14-54 nm indicando que los sólidos corresponden a sistemas nanométricos. Los ensayos catalíticos en la reacción de reformado de metano con vapor indicaron que la sustitución de Ni por metales nobles favorece la conversión de CH4 y la producción de H2, minimizando la formación de carbón. El catalizador que mostro mejor actividad fue el modificado con Ru. Los sólidos substituidos con Ga mostraron una baja actividad catalítica.

ChemInform, Aug 20, 2010

ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Journal of Catalysis, Oct 1, 1997

The isomerization and metathesis of cyclopropane were carried out over a series of reduced molybd... more The isomerization and metathesis of cyclopropane were carried out over a series of reduced molybdena-alumina catalysts (1.7-13 wt% Mo). The distribution of Mo oxidation states was determined by XPS. The average Mo oxidation state estimated from XPS agreed with that obtained by measuring the O 2 consumption on reoxidation for a given catalyst. A good correlation was found between the catalytic activity for the isomerization reaction and the relative intensity of the XPS peak attributed to paired double-bonded Mo (IV) species (as in MoO 2). The results indicate a direct relationship between these Mo (IV) species and the coordinative unsaturated sites involved in the formation of metallocyclobutane. The latter is reportedly the intermediate required for the isomerization reaction to take place.

HAL (Le Centre pour la Communication Scientifique Directe), 2006

An investigation of bulk and cobalt or ruthenium supported tungsten carbide was carried out for t... more An investigation of bulk and cobalt or ruthenium supported tungsten carbide was carried out for their use in the Fischer-Tropsch reaction. Two types of WC were studied : tungsten carbide protected by free carbon and clean tungsten carbide, respectively noticed WC(A) and WC(B). XPS analysis shows that after air exposure, the WC(A) carbide surface is protected from the excess carbon whereas a surface W 6+ phase is induced during the passivation step for WC(B). However WC(A) is inert towards aqueous impregnation, whereas WC(B) starts to corrode. A reduction in hydrogen at 673 K for Ru and 773K for Co supported catalysts allows obtaining Co 0 and Ru 0 dispersed on layers of free carbon covering the WC core for WC(A) and on a surface free of oxygen for WC(B). All the catalysts were active for the FT reaction. WC(A) produces mainly light alkanes (78%) and alcohols (22%), whereas no alcohol production is observed for WC(B). Co/WC(B) has a better activity than Co/WC(A), due to a better dispersion of cobalt on WC(B). The addition of Ru on WC(A) allow to obtain an high active catalyst with production of heavy hydrocarbons. On the contrary, formation of a Ru-W alloy could be consider to explain the low activity of Ru/WC(B) catalyst.

Journal of Power Sources, Jul 1, 2015

We synthesize and evaluate catalysts to produce diesel fraction components in FTS. Pore diameter ... more We synthesize and evaluate catalysts to produce diesel fraction components in FTS. Pore diameter significantly influences the liquid products distribution. The catalyst with smaller pore size showed a deviation from the ASF mechanism.

Applied Catalysis A-general, Sep 1, 2018

Ni 0-particles (24-49 nm) Oxides matrix: La 2 O 2 CO 3-MnO  Mn 2 O 3 CH 4 H 2 C CH 4 + CO 2 CO +... more Ni 0-particles (24-49 nm) Oxides matrix: La 2 O 2 CO 3-MnO  Mn 2 O 3 CH 4 H 2 C CH 4 + CO 2 CO +H 2 + CO 2 CO C + H 2 O CO Highlights  The partial replacement of nickel by manganese gives rise to high thermal stability solids.  The enhanced interaction between Ni and La2O2CO3 by Mn-doping suppresses sintering of nickel particles during DRM.  Ni-dopant quantity on the LaMnO3 sample promotes its activation to high CH4 and CO2 conversions.  La2O2CO3 act as an active intermediate of La2O3 to suppress deposited coke.  The catalysts inhibit carbon formation despite the severe reaction conditions Abstract A series of ternary perovskite-type oxides LaNi1-xMnxO3 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) were synthesized by the sol-gel resin method in propionic acid, producing solids solutions of perovskite-type structures with crystallite sizes between 15-20 nm. The LaNi1-xMnxO3 catalysts were thoroughly characterized and tested in the catalytic dry reforming of methane (DRM) reaction. It was observed that the presence of Mn in the perovskite-type oxide increases the Ni 3+ to Ni 0 reduction temperature giving rise to formation of Ni 0 nanoparticles on the MnOx-La2O3 matrix. The LaNi1-xMnxO3 with x ≤ 0.8 showed higher activities and selectivity's towards syngas during the CH4-CO2 reforming, due to in situ formation of highly dispersed Ni 0-metallic nanoparticles on the La2O2CO3-MnO-Mn2O3 solid matrix responsible for the high activity and high resistance to carbon buildup on the catalyst surface.

Catalysis Today, Apr 1, 2008

The preparation of three different types of mixed nickel oxides is described. These systems inclu... more The preparation of three different types of mixed nickel oxides is described. These systems include: (i) the perovskite LaNiO3 oxide, (ii) a mixed-oxide derived from a hydrotalcite Ni–Al (64:38) precursor, and (iii) the spinel-type NiAl2O4 oxide. These systems were prepared with the aim of studying the activation procedure that develops small nickel nanoparticles deposited on a La2O3 or Al2O3 substrate

Chemischer Informationsdienst, Oct 3, 1978

Zeolites, 1989

The chemistry of Ru(lll) hexaamine complex imbedded in zeolite has been investigated by e.s.r., i... more The chemistry of Ru(lll) hexaamine complex imbedded in zeolite has been investigated by e.s.r., i.r., and other techniques. Zeolite-supported Ru(III)(NH3)6 exhibited e.s.r, signal characteristic for four d s low-spin configuration species in an octahedral tetragonally distorted crystal field symmetry. Upon thermal activation, change from axial to orthorhombic symmetry occurred. I.r. analysis in the iSNH3 region also indicated that the symmetry of the NH3 ligand coordination sphere was lowered upon thermal activation. Activation at temperature higher than 523 K resulted in the formation of RuOx species. The results will be discussed in terms of rapid hydrolysis of the cationic Ru(lll), with the subsequent formation of ruthenium red complexes that were decomposed into ruthenium oxide at higher temperature. The stability of Ru(III)(NH3)s toward hydrolysis depended on the zeolite type used. Finally, we report that the dispersion of the Ru metal, formed upon H2 reduction, was controlled by the state of the dispersion of the oxidized Ru.

HAL (Le Centre pour la Communication Scientifique Directe), 2005

HAL (Le Centre pour la Communication Scientifique Directe), 2005

... Due to the high temperatures involved and the presence of steam, sinterization of the active ... more ... Due to the high temperatures involved and the presence of steam, sinterization of the active metal species and coke formation lead to catalysts deactivation and in some cases to plugging of the reactor [10]. ... catalyst stability; • coke formation by the following two reactions: ...

Studies in Surface Science and Catalysis, 2000

Resumen es: Se estudiaron una serie de precursores tipo perovskita (La 1-x Sr x CoO 3 con x = 0; ... more Resumen es: Se estudiaron una serie de precursores tipo perovskita (La 1-x Sr x CoO 3 con x = 0; 0,2; 0,4), preparados por el metodo de auto-combustion y caracteri...

Elsevier eBooks, 1993

Abstract A laterite iron mineral has been modified to obtain a K and Mn promoted laterite based c... more Abstract A laterite iron mineral has been modified to obtain a K and Mn promoted laterite based catalyst for CO hydrogenation reaction. Catalytic tests were conducted at atmospheric and higher pressure at 280–300 °C in fixed bed reactor systems. Characterization of the solids indicate a high influence of promotors on the Fe phases present on the catalysts. Mn inhibits formation of carbidic phases while the presence of K accelerates this effect. The double promoted laterite produces an active and stable solid with high selectivity to the C 2 -C 4 olefin fraction.

HAL (Le Centre pour la Communication Scientifique Directe), 2006

An investigation of the performances in Fischer-Tropsch reaction of 1wt% M/WC(X) (M = Co, Ru; X =... more An investigation of the performances in Fischer-Tropsch reaction of 1wt% M/WC(X) (M = Co, Ru; X = A, B), where A is a tungsten carbide protected by free carbon and B is a clean tungsten carbide, was carried out. Supported catalysts performances were compared to those of the parent tungsten carbides at 473 K and 20 bar. It was found that WC(A) produces mainly hydrocarbons but also 20-40% alcohols, whereas WC(B) activity is only towards linear alkanes. Before catalytic test, a reduction in pure hydrogen allows obtaining Co 0 and Ru 0 dispersed on layers of free carbon covering the WC core for the WC(A), and on a surface free of oxygen for WC(B). Co as Ru dispersions are improved on WC(B) compared to WC(A). A direct consequence is that Co/WC(B) has a better activity than Co/WC(A). Ru-W alloy formation could be responsible of the inobservance of a better activity for Ru/WC(B). On contrary, addition of Ru on WC(A) highly increases the activity and the production of heavy hydrocarbons. This beneficial effect, not observed with cobalt, could be attributed to a better dispersion of ruthenium on a carbon polymeric surface of WC.

Hyperfine Interactions, Dec 1, 1994

The syngas reaction has been studied using a laterite iron mineral, promoted with K and Mn. In si... more The syngas reaction has been studied using a laterite iron mineral, promoted with K and Mn. In situ activation under syngas, as well as pre-treatment with H2 followed by CO under mild and more severe conditions were tested. These activation procedures led to different iron phase compositions and to different catalytic selectivities. The C2-C4/CH4 ratio was significantly lower for those catalysts which after reaction showed the presence of hexagonal carbide and magnetite compared to the solid, which showed the highest proportion of Hagg carbide.

Journal of Catalysis, Jun 1, 1992

ABSTRACT

Applied Catalysis A-general, Oct 1, 1992

The effect of a deposit of 1 wt.-% vanadium on the physicochemical and catalytic properties of a ... more The effect of a deposit of 1 wt.-% vanadium on the physicochemical and catalytic properties of a USHY zeolite and of a FCC catalyst has been determined by various techniques: X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and methylcyclohexane transformation. With USHY and whatever the pretreatment: calcination under dry air flow at 546' C or hydrothermal treatment at 750' C, vanadium is well dispersed while in the FCC catalyst it is in the form of large aggregates (6 to 12 nm). The hydrothermal treatment causes a partial elimination of vanadium from the sample and a decrease of the surface concentration of vanadium. The matrix of the FCC catalyst limits the formation or/and the migration of the volatile vanadium species. Vanadium decreases the stability of the zeolite (decrease in crystallinity and increase of the deal~ination rate during the hydrothermal treatment) and consequently the activity of the zeolite and FCC catalyst samples. However this decrease in activity seems to be due partly to other phenomena, particularly to the exchange of the protonic sites by cationic vanadium species.

Se sintetizaron sólidos tipo espinelas modificados con sustitución parcial y completa de Al por G... more Se sintetizaron sólidos tipo espinelas modificados con sustitución parcial y completa de Al por Ga, y con sustitución parcial de Ni por metales nobles, mediante el método sol-gel de citrato. Las espinelas fueron utilizadas como soportes de catalizadores de Ni en diferentes proporciones (5, 10 y 15%). Los sólidos fueron caracterizados por técnicas tales como DRX, área específica BET y análisis termogravimétrico ATG. Se obtuvieron tamaños de partículas entre 14-54 nm indicando que los sólidos corresponden a sistemas nanométricos. Los ensayos catalíticos en la reacción de reformado de metano con vapor indicaron que la sustitución de Ni por metales nobles favorece la conversión de CH4 y la producción de H2, minimizando la formación de carbón. El catalizador que mostro mejor actividad fue el modificado con Ru. Los sólidos substituidos con Ga mostraron una baja actividad catalítica.

ChemInform, Aug 20, 2010

ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Journal of Catalysis, Oct 1, 1997

The isomerization and metathesis of cyclopropane were carried out over a series of reduced molybd... more The isomerization and metathesis of cyclopropane were carried out over a series of reduced molybdena-alumina catalysts (1.7-13 wt% Mo). The distribution of Mo oxidation states was determined by XPS. The average Mo oxidation state estimated from XPS agreed with that obtained by measuring the O 2 consumption on reoxidation for a given catalyst. A good correlation was found between the catalytic activity for the isomerization reaction and the relative intensity of the XPS peak attributed to paired double-bonded Mo (IV) species (as in MoO 2). The results indicate a direct relationship between these Mo (IV) species and the coordinative unsaturated sites involved in the formation of metallocyclobutane. The latter is reportedly the intermediate required for the isomerization reaction to take place.

HAL (Le Centre pour la Communication Scientifique Directe), 2006

An investigation of bulk and cobalt or ruthenium supported tungsten carbide was carried out for t... more An investigation of bulk and cobalt or ruthenium supported tungsten carbide was carried out for their use in the Fischer-Tropsch reaction. Two types of WC were studied : tungsten carbide protected by free carbon and clean tungsten carbide, respectively noticed WC(A) and WC(B). XPS analysis shows that after air exposure, the WC(A) carbide surface is protected from the excess carbon whereas a surface W 6+ phase is induced during the passivation step for WC(B). However WC(A) is inert towards aqueous impregnation, whereas WC(B) starts to corrode. A reduction in hydrogen at 673 K for Ru and 773K for Co supported catalysts allows obtaining Co 0 and Ru 0 dispersed on layers of free carbon covering the WC core for WC(A) and on a surface free of oxygen for WC(B). All the catalysts were active for the FT reaction. WC(A) produces mainly light alkanes (78%) and alcohols (22%), whereas no alcohol production is observed for WC(B). Co/WC(B) has a better activity than Co/WC(A), due to a better dispersion of cobalt on WC(B). The addition of Ru on WC(A) allow to obtain an high active catalyst with production of heavy hydrocarbons. On the contrary, formation of a Ru-W alloy could be consider to explain the low activity of Ru/WC(B) catalyst.

Journal of Power Sources, Jul 1, 2015

We synthesize and evaluate catalysts to produce diesel fraction components in FTS. Pore diameter ... more We synthesize and evaluate catalysts to produce diesel fraction components in FTS. Pore diameter significantly influences the liquid products distribution. The catalyst with smaller pore size showed a deviation from the ASF mechanism.

Applied Catalysis A-general, Sep 1, 2018

Ni 0-particles (24-49 nm) Oxides matrix: La 2 O 2 CO 3-MnO  Mn 2 O 3 CH 4 H 2 C CH 4 + CO 2 CO +... more Ni 0-particles (24-49 nm) Oxides matrix: La 2 O 2 CO 3-MnO  Mn 2 O 3 CH 4 H 2 C CH 4 + CO 2 CO +H 2 + CO 2 CO C + H 2 O CO Highlights  The partial replacement of nickel by manganese gives rise to high thermal stability solids.  The enhanced interaction between Ni and La2O2CO3 by Mn-doping suppresses sintering of nickel particles during DRM.  Ni-dopant quantity on the LaMnO3 sample promotes its activation to high CH4 and CO2 conversions.  La2O2CO3 act as an active intermediate of La2O3 to suppress deposited coke.  The catalysts inhibit carbon formation despite the severe reaction conditions Abstract A series of ternary perovskite-type oxides LaNi1-xMnxO3 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) were synthesized by the sol-gel resin method in propionic acid, producing solids solutions of perovskite-type structures with crystallite sizes between 15-20 nm. The LaNi1-xMnxO3 catalysts were thoroughly characterized and tested in the catalytic dry reforming of methane (DRM) reaction. It was observed that the presence of Mn in the perovskite-type oxide increases the Ni 3+ to Ni 0 reduction temperature giving rise to formation of Ni 0 nanoparticles on the MnOx-La2O3 matrix. The LaNi1-xMnxO3 with x ≤ 0.8 showed higher activities and selectivity's towards syngas during the CH4-CO2 reforming, due to in situ formation of highly dispersed Ni 0-metallic nanoparticles on the La2O2CO3-MnO-Mn2O3 solid matrix responsible for the high activity and high resistance to carbon buildup on the catalyst surface.

Catalysis Today, Apr 1, 2008

The preparation of three different types of mixed nickel oxides is described. These systems inclu... more The preparation of three different types of mixed nickel oxides is described. These systems include: (i) the perovskite LaNiO3 oxide, (ii) a mixed-oxide derived from a hydrotalcite Ni–Al (64:38) precursor, and (iii) the spinel-type NiAl2O4 oxide. These systems were prepared with the aim of studying the activation procedure that develops small nickel nanoparticles deposited on a La2O3 or Al2O3 substrate

Chemischer Informationsdienst, Oct 3, 1978

Zeolites, 1989

The chemistry of Ru(lll) hexaamine complex imbedded in zeolite has been investigated by e.s.r., i... more The chemistry of Ru(lll) hexaamine complex imbedded in zeolite has been investigated by e.s.r., i.r., and other techniques. Zeolite-supported Ru(III)(NH3)6 exhibited e.s.r, signal characteristic for four d s low-spin configuration species in an octahedral tetragonally distorted crystal field symmetry. Upon thermal activation, change from axial to orthorhombic symmetry occurred. I.r. analysis in the iSNH3 region also indicated that the symmetry of the NH3 ligand coordination sphere was lowered upon thermal activation. Activation at temperature higher than 523 K resulted in the formation of RuOx species. The results will be discussed in terms of rapid hydrolysis of the cationic Ru(lll), with the subsequent formation of ruthenium red complexes that were decomposed into ruthenium oxide at higher temperature. The stability of Ru(III)(NH3)s toward hydrolysis depended on the zeolite type used. Finally, we report that the dispersion of the Ru metal, formed upon H2 reduction, was controlled by the state of the dispersion of the oxidized Ru.