Catalytic upgrading of clean biogas to synthesis gas

Clean biogas, produced by anaerobic digestion of biomasses or organic wastes, is one of the most promising substitutes for natural gas. After its purification, it can be valorized through different reforming processes that convert CH4 and CO2 into synthesis gas (a mixture of CO and H2). However, these processes have many issues related to the harsh conditions of reaction used, the high carbon formation rate and the remarkable endothermicity of the reforming reactions. In this context, the use of the appropriate catalyst is of paramount importance to avoid deactivation, to deal with heat issues and mild reaction conditions and to attain an exploitable syngas composition. The development of a catalyst with high activity and stability can be achieved using different active phases, catalytic supports, promoters, preparation methods and catalyst configurations. In this paper, a review of the recent findings in biogas reforming is presented. The different elements that compose the catalytic system are systematically reviewed with particular attention on the new findings that allow to obtain catalysts with high activity, stability, and resistance towards carbon formation

Ru–CeO2 and Ni–CeO2 Coated on Open-Cell Metallic Foams by Electrodeposition for the CO2 Methanation

CO2 methanation structured catalysts, made by a layer of Ru–CeO2 or Ni–CeO2 (Ru/Ce = 3/97; Ni/Ce = 1/3 and 3/1) on open-cell NiCrAl foams, are prepared by electrodeposition and a subsequent calcination step. The performance of the catalysts at a space velocity of 320,000 mL gcat–1 h–1 in a feedstock with H2/CO2/N2 = 4/1/1 v/v, significantly depends on the Ni content and the preparation method. A low Ru or Ni content promotes the metal–CeO2 interaction, the formation of defects in CeO2 as well as the development of a lower amount of cracks in the coating; however, the catalysts show a poor CO2 conversion and selectivity to CH4. The CH4 production rate at low temperature largely increases for the high Ni loaded catalyst, 68.7 LCH4 gNi–1 h–1 at 350 °C oven temperature. This productivity is similar to the value obtained with a Ni3Ce1 pellet catalyst prepared by the coprecipitation method, a behavior not achievable for low Ru- and Ni-loaded catalysts

Promotion effect of rare earth elements (Ce, Nd, Pr) on physicochemical properties of M-Al mixed oxides (M = Cu, Ni, Co) and their catalytic activity in N2O decomposition

A series of M-AlOx mixed oxides (M = Cu, Co, Ni) with the addition of high loadings of rare earth elements (REE, R = Ce, Nd, Pr; R0.5M0.8Al0.2, molar ratio) were investigated in N2O decomposition. The precursors were prepared by coprecipitation and subsequent calcination at 600\ua0\ub0C. The obtained mixed metal oxides were characterized by X-ray diffraction with Rietveld analysis, N2 sorption, and H2 temperature-programmed reduction. Depending on the nature of REE and the initial M-Al system, R cations could be separately segregated in oxide form or coordinated with the transition metal cations and form mixed structures. The addition of Ce3+ consistently led to nanocrystalline CeO2 mixed with the divalent oxides, whereas the addition of Nd3+ or Pr3+ resulted in the formation of their respective oxide phases as well as perovskites/Ruddlesden–Popper phases. The presence of REE modified the textural and redox properties of the calcined materials. The rare earth element-induced formation of low-temperature reducible MOx species that systematically improved the N2O decomposition on the modified catalysts compared to the pristine M-Al materials by the order of Co > Ni > Cu. The Ce0.5Co0.8Al0.2 catalyst revealed the highest activity and remained stable (approximately 90% of N2O conversion) for 50\ua0h during time-on-stream in 1000\ua0ppm N2O, 200\ua0ppm NO, 20 000\ua0ppm O2, 2500\ua0ppm H2O/N2 balance at WHSV = 16 L g−1\ua0h−1

Efficient low-loaded ternary Pd-In2O3-Al2O3 catalysts for methanol production

Pd-In2O3 catalysts are among the most promising alternatives to Cu-ZnO-Al2O3 for synthesis of CH3OH from CO2. However, the intrinsic activity and stability of In2O3 per unit mass should be increased to reduce the content of this scarcely available element and to enhance the catalyst lifetime. Herein, we propose and demonstrate a strategy for obtaining highly dispersed Pd and In2O3 nanoparticles onto an Al2O3 matrix by a one-step coprecipitation followed by calcination and activation. The activity of this catalyst is comparable with that of a Pd-In2O3 catalyst (0.52 vs 0.55 gMeOH h−1 gcat-1 at 300 \ub0C, 30 bar, 40,800 mL h−1 gcat-1) but the In2O3 loading decreases from 98 to 12 wt% while improving the long-term stability by threefold at 30 bar. In the new Pd-In2O3-Al2O3 system, the intrinsic activity of In2O3 is highly increased both in terms of STY normalized to In specific surface area and In2O3 mass (4.32 vs 0.56 g gMeOH h−1 gIn2O3-1 of a Pd- In2O3 catalyst operating at 300 \ub0C, 30 bar, 40,800 mL h−1 gcat-1).The combination of ex situ and in situ catalyst characterizations during reduction provides insights into the interaction between Pd and In and with the support. The enhanced activity is likely related to the close proximity of Pd and In2O3, wherein the H2 splitting activity of Pd promotes, in combination with CO2 activation over highly dispersed In2O3 particles, facile formation of CH3OH

A High Pressure Operando Spectroscopy Examination of Bimetal Interactions in ‘Metal Efficient’ Palladium/In2O3/Al2O3 Catalysts for CO2 Hydrogenation

CO2 hydrogenation to methanol has the potential to serve as a sustainable route to a wide variety of hydrocarbons, fuels and plastics in the quest for net zero. Synergistic Pd/In2O3 (Palldium on Indium Oxide) catalysts show high CO2 conversion and methanol selectivity, enhancing methanol yield. The identity of the optimal active site for this reaction is unclear, either as a Pd−In alloy, proximate metals, or distinct sites. In this work, we demonstrate that metal-efficient Pd/In2O3 species dispersed on Al2O3 can match the performance of pure Pd/In2O3 systems. Further, we follow the evolution of both Pd and In sites, and surface species, under operando reaction conditions using X-ray Absorption Spectroscpy (XAS) and infrared (IR) spectroscopy. In doing so, we can determine both the nature of the active sites and the influence on the catalytic mechanism

A high pressure operando spectroscopy examination of bimetal interactions in ‘Metal Efficient’ palladium/In 2 O 3 /Al 2 O 3 catalysts for CO 2 hydrogenation

CO2 hydrogenation to methanol has the potential to serve as a sustainable route to a wide variety of hydrocarbons, fuels and plastics in the quest for net zero. Synergistic Pd/In2O3 (Palldium on Indium Oxide) catalysts show high CO2 conversion and methanol selectivity, enhancing methanol yield. The identity of the optimal active site for this reaction is unclear, either as a Pd−In alloy, proximate metals, or distinct sites. In this work, we demonstrate that metal‐efficient Pd/In2O3 species dispersed on Al2O3 can match the performance of pure Pd/In2O3 systems. Further, we follow the evolution of both Pd and In sites, and surface species, under operando reaction conditions using X‐ray Absorption Spectroscpy (XAS) and infrared (IR) spectroscopy. In doing so, we can determine both the nature of the active sites and the influence on the catalytic mechanism

Giacomo di Vitry guadagnato alla storia. Alcune riflessioni su due opere recenti

La pubblicazione analizza due opere di Giacomo di Vitry, pubblicate in edizione critica da Brepols, Turnhout (BE), e cio\ue8 i primi 36 Sermones uulgares uel ad status nell'edizione di J. Long\ue8re e la Vita di Maria di Oignies e il Supplementum di Tommaso di Cantimpr\ue9 tradotti in lingua tedesca da Iris Geyer dall'edizione critica di R.B.C. Huygens

Viaggio al centro del Medioevo. Questioni, luoghi, personaggi

Il volume, attento all'epistemologia e alla metodologia storiografica, \ue8 contrassegnato da una forte attenzione nei confronti di alcuni "protagonisti" del mondo medievale, e in particolare di Pier Damiani, di Gregorio VII, di Urbano II, di Bernardo di Clairvaux, e via dicendo, n\ue9 vi sono trascurate acune rilevanze di carattere "ereticale". Nella prospettiva di una riflessione che si estenda anche alle zone di confine dell'Adriatico nordorientale nel corso del Medioevo, sono indagati con vivo interesse alcuni personaggi e alcune tematiche tipiche della "frontiera": Paolino di Aquileia, Paolo Diacono, alcuni Salteri, e diverse problematiche connesse con la storia medievale degli Slavi del sud (e in particolare con la loro cristianizzazione) concludono una trattazione piuttosto ricca, ma tuttavia sostanzialmente "aperta" ad ulteriori sviluppi

Kurt Reindel, éd. — Die Briefe des Petrus Damiani. III : 91-150. Munich, M.G.H., 1989.

Fornasari Giuseppe. Kurt Reindel, éd. — Die Briefe des Petrus Damiani. III : 91-150. Munich, M.G.H., 1989.. In: Cahiers de civilisation médiévale, 37e année (n°145-146), Janvier-juin 1994. Henri II Plantagenêt et son temps. Actes du Colloque de Fontevraud. 29 septembre – 1er octobre 1990. pp. 154-156