Synthetic Hydrotalcites as suitable Co-based catalysts for Fischer-Tropsch Process

Nowadays it is imperative to develop economical and energy-efficient processes for the sustainable production of alternative fuels and chemicals. Fischer Tropsch synthesis (FT) is a well-established industrial process whereby these objectives can be achieved using syngas (mixture of H2, CO, CO2) as raw material. Syngas can be manufactured from CH4, coal or, as a new tendency, frombiomass. FT synthesis usually requires catalysts based on cobalt or iron. The typical products range is from methane to long chain hydrocarbons (waxes) [1]. Cobalt-based catalysts have been used for FT for long time due to their long life-times, high CO conversion and high selectivity to heavy hydrocarbons; they are moreover characterized by low activity towards the water-gas shift, so avoiding the CO2 formation. In this work, layered double or triple hydroxides, also known as synthetic hydrotalcites, are proposed and studied as FT catalysts. The choice of these materials allows to easily prepare solid phases, essentially based on mixed metal oxides, where specific metal atoms are homogeneously dispersed at an atomic level. Hydrotalcites are represented by the empirical formula [M(II)1-xM(III)x(OH)2]x+[An-x/n]x-mH2O where M(II) is a divalent cation such as Co, Mg, Zn, Ni, or Cu, M(III) is a trivalent cation such as Al, Cr, Fe or Ga; An- is an anion of charge n and m the molar amounts of co-intercalated water [2]. When calcined at proper temperatures, the random distribution of cations, characteristic of the hydroxide phase, is maintained in the resulting mixed oxide. Hydrotalcite based materials have been recently reported as good catalysts for several processes in the energy field, such as hydrogen production by steam reforming of methanol and ethanol, photocatalytic water splitting and so on [3-5]. A series a Co-Zn-Al hydrotalcites, with increasing Co contents was synthesized and characterized. Preliminary tests on their catalytic activity in the FT process resulted in a satisfactory outcome

The “Historical Materials BAG”: A New Facilitated Access to Synchrotron X-ray Diffraction Analyses for Cultural Heritage Materials at the European Synchrotron Radiation Facility

The European Synchrotron Radiation Facility (ESRF) has recently commissioned the new Extremely Brilliant Source (EBS). The gain in brightness as well as the continuous development of beamline instruments boosts the beamline performances, in particular in terms of accelerated data acquisition. This has motivated the development of new access modes as an alternative to standard proposals for access to beamtime, in particular via the “block allocation group” (BAG) mode. Here, we present the recently implemented “historical materials BAG”: a community proposal giving to 10 European institutes the opportunity for guaranteed beamtime at two X-ray powder diffraction (XRPD) beamlines—ID13, for 2D high lateral resolution XRPD mapping, and ID22 for high angular resolution XRPD bulk analyses—with a particular focus on applications to cultural heritage. The capabilities offered by these instruments, the specific hardware and software developments to facilitate and speed-up data acquisition and data processing are detailed, and the first results from this new access are illustrated with recent applications to pigments, paintings, ceramics and wood

Harnessing the NEON data revolution to advance open environmental science with a diverse and data-capable community

It is a critical time to reflect on the National Ecological Observatory Network (NEON) science to date as well as envision what research can be done right now with NEON (and other) data and what training is needed to enable a diverse user community. NEON became fully operational in May 2019 and has pivoted from planning and construction to operation and maintenance. In this overview, the history of and foundational thinking around NEON are discussed. A framework of open science is described with a discussion of how NEON can be situated as part of a larger data constellation—across existing networks and different suites of ecological measurements and sensors. Next, a synthesis of early NEON science, based on >100 existing publications, funded proposal efforts, and emergent science at the very first NEON Science Summit (hosted by Earth Lab at the University of Colorado Boulder in October 2019) is provided. Key questions that the ecology community will address with NEON data in the next 10 yr are outlined, from understanding drivers of biodiversity across spatial and temporal scales to defining complex feedback mechanisms in human–environmental systems. Last, the essential elements needed to engage and support a diverse and inclusive NEON user community are highlighted: training resources and tools that are openly available, funding for broad community engagement initiatives, and a mechanism to share and advertise those opportunities. NEON users require both the skills to work with NEON data and the ecological or environmental science domain knowledge to understand and interpret them. This paper synthesizes early directions in the community’s use of NEON data, and opportunities for the next 10 yr of NEON operations in emergent science themes, open science best practices, education and training, and community building

On the role of non-covalent interactions in the assembly of 3D zirconium methyl- and ethyl-N,N-bis phosphonates

Novel Zr methyl- and ethyl-N,N-bis(methylphosphonates), with formula ZrF2[(O3PCH2)2NHCH3] and Zr[(HO3PCH2)(O3PCH2)NHC 2H5]2, respectively, were prepared in mild solvothermal conditions and their structures were solved ab initio by laboratory X-ray powder diffraction data. Despite the chemical homology between the molecular building blocks, and the similar synthetic conditions, the two compounds showed different stoichiometry and crystal structure. A comparative analysis of these structures and that of homologous longer chain Zr phosphonates, previously reported, revealed the important contribution of the hydrophobic groups in the building of the crystal structure, in a way that can be compared to that observed in the assembly of amphiphilic systems. © The Royal Society of Chemistry 2013

Dimensional reduction in zirconium phosphate; from layers to ribbons to chains

Two new one-dimensional zirconium phosphate fluorides, Zr[(NH4)2PO4]2F 2\ub7H2O (1) and Zr(NH4PO4)[(NH4)2PO 4]F\ub70.5H2O (2), have been synthesized via decomposition of zirconium fiuoride complexes. Their structures were determined by single crystal and X-ray powder diffraction, respectively. The structure of 1 is made of infinite single chains composed of insular Zr octahedra vertex-linked to four PO4 tetrahedra. Each zirconium is trans-coordinated to two F atoms. The structure of 2 is composed of double chains that can be seen as two condensed single chains of 1, with the elimination of a fluorine atom from the zirconium coordination sphere. Zirconium is octahedrally coordinated, with three triply connected and two doubly connected phosphate tetrahedra, and with a fluorine atom. The structural connection between 1, 2, and layered \u3b1- and \u3b3-zirconium phosphates is discussed and verified by interconversion experiments. 1 was found to convert into 2 after ageing in its mother liquor, while 2 can be converted into \u3b1-ZrP in acidic media. 1 and 2 were found to swell and form stable colloidal dispersions on elution with 0.1 M hydrochloric acid solution. These properties make these one-dimensional zirconium phosphates interesting compounds for application in nanocomposite materiais synthesis

Synthesis and Crystal Structure from X-ray Powder Diffraction Data of Two Zirconium Diphosphonates Containing Piperazine Groups

Two new zirconium aminophosphonates have been obtained by reaction of Zr(IV) with piperazine-N,N′-bis(methylenephosphonate) building blocks. Their crystal structure has been determined ab initio from X-ray powder diffraction data collected with a conventional diffractometer. Although prepared in similar conditions, their composition and crystal structure is markedly different. Compound 1, of formula Zr2H4[(O3PCH2)2N2C4H8]3·9H2O, has a three-dimensional structure (trigonal, space group R3̅̅ (No. 148), a = 19.9400(9) Å, c = 9.5728(6) Å, Z = 3), made of infinite inorganic chains of ZrO6 octahedra and PO3C tetrahedra, running along the c-axis direction, connected by piperazine groups in the ab plane, and generating channels running along the c axis. Compound 2, of formula ZrF2(O3PCH2)2(NH)2C4H8, has a pillared-layered structure (monoclinic, space group P21/c (No. 14), a = 8.7148(2) Å, b = 8.1731(1) Å, c = 9.0134(2) Å, β = 105.175(1)° Z = 2) in which inorganic layers, made of the connectivity of Zr octahedra and P tetrahedra, are covalently connected by piperazine groups, that act as pillars. The effect of the various synthesis parameters is discussed. A probable structure directing parameter seems to be the pH value of the starting precipitation solution, that can influence the protonation of N atoms of piperazine moiety

New hybrid zirconium aminophosphonates containing piperidine and bipiperidine groups

The reaction of N-(phosphonomethyl)piperidine and N,N′- bis(phosphonomethyl)bipiperidine with zirconium(IV) in hydrofluoric acid media led to the preparation of two new zirconium fluoride phosphonate derivatives with 1D and 2D structure, respectively. Their structures were solved ab initio from laboratory powder X-ray diffraction (PXRD) data. The monophosphonate derivative, with formula ZrF2(HF)(O3PCH2NC 5H10), has a 1D structure (triclinic, space group P1̄, a = 6.6484(3) Å, b = 7.1396(3) Å, c = 12.2320(6) Å, α = 77.932(4)°, β = 87.031(6)°, γ = 78.953(5)°, V = 557.22(4) Å3, and Z = 2) made of inorganic chains constituted from the connection of zirconium octahedra and phosphorus tetrahedra with the piperidine groups bonded on their external part. The diphosphonate derivative, with formula Zr2F4(HF)2(O3PCH 2)NC10H18N(CH2PO3), has a 2D structure (triclinic, space group P1̄, a = 6.6243(3) Å, b = 7.2472(4) Å, c = 12.2550(7) Å, α = 102.879(4)°, β = 100.29(1)°, γ = 101.287(7)°, V = 547.03(4) Å3, and Z = 1) composed of the packing of covalent layers whose structure may be ideally obtained by the joining of adjacent chains of the 1D compound. In these hybrid layers, inorganic regions made of the connectivity of zirconium octahedra and phosphorus tetrahedra alternate with organic regions represented by the bipiperidine moieties. A section dedicated to vibrational spectroscopy analysis is also included, mainly devoted to clarify some issues not easily deducible on the basis of PXRD data and to describe the fluorine environment inside zirconium phosphonate structures. © 2011 American Chemical Society

Design and synthesis of plasticizing fillers based on zirconium phosphonates for glycerol-free composite starch films

Novel starch-based composite films were prepared by solution casting from gelatinized starch, using a new class of layered zirconium hydroxyalkyl aminophosphonates, ZrF(O 3PCH 2) 2NH(CH 2) nOH (n = 3, 4, 5), as fillers/plasticizers. These compounds were specifically designed and synthesized for this application in order to support organic polar groups, able to interact with the polymer, on robust inorganic layers. Their structures were solved ab initio from powder X-ray diffraction data. The films, loaded with 2 wt% of fillers, were studied by means of various techniques such as X-ray diffraction, scanning and transmission electron microscopy, thermogravimetry, and stress-strain tests. The obtained results highlighted the double role played by the fillers as a reinforcement for the polymer matrix and as plasticizing agents: the composites showed improved thermal and mechanical properties, along with a significant reduction of volume swelling, if compared with the glycerol-plasticized films. © 2012 The Royal Society of Chemistry