Influence of Ni content on physico-chemical characteristics of Ni, Mg, Al-Hydrotalcite like compounds

Abstract

The physico-chemical properties of a series of Ni,Mg,Al-HTLC with Al/(Al+Mg+Ni) = 0.25 and low Ni/Mg ratios were studied by means of X-ray diffraction (XRD), thermogravimetric (TGA) and thermodifferential (DTA) analysis, N2 physissorption and temperature programmed reduction (TPR). The as-synthesized materials were well-crystallized, with XRD patterns typical of the HTLCs in carbonate form. Upon calcination and dehydration the dehydroxilation of the layers with concurrent decomposition of carbonate anions produced mixed oxides with high surface area. XRD analysis indicated that the different nickel and aluminum oxides species are well-dispersed in a poor-crystallized MgO periclase-type phase. As observed by TPR, the different Ni species showed distinct interactions with Mg(Al)O phase, which were influenced by both nickel content and calcination temperature. Regardless of the the nickel content, the reduction of nickel species was not complete as indicated by the presence of metallic dispersions

Catalytic Response and Stability of Nickel/Alumina for the Hydrogenation of 5‐Hydroxymethylfurfural in Water

“…[37] Arepresentative SEM image using NiAl-4P as example is presentedi nF igure 2a where the lamellar/platelet morphology observed for the four samples is characteristico fawell-developed layered structure. EDX measurements confirm the homogeneity of the samples, and the Al ratios (Table1)a re close (AE 8%)t ot hose obtained by ICP.T he Brunauer-Emmett-Teller (BET) surface areas (SA = 65-107 m 2 g À1 ,T able 1) are within the range of values reported in the literature for Ni-Al layer double hydroxides( 15-98m 2 g À1 ) [38][39][40] and increase with the Al content whereas the crystallite size (d LDH = 10 nm) remains constant. …”

Gas-phase toluene oxidation over platinum-containing mixed oxides

“…The calcined sample exhibited, as expected, high surface area (201 m 2 /g), which can be mainly due to the formation of mesopores associated to the elimination of carbonate anions, as CO 2 , leading to partial destruction of the layered structure [12].…”

“…The synthesis procedure is described elsewhere [12]. The hydrotalcite thus obtained was then dried at 353 K overnight.…”

Hidropirólise solar da microalga Chlamydomonas reinhardtii combinada com o precursor catalítico tipo Hidrotalcita

“…De acordo com a época do ano em que os experimentos de hidropirólise seriam realizados e informações de (CAVANI et al, 1991;LEBEDEVA et al, 1999). (WIYANTOKO et al, 2015;NAVARRO et al, 2018;RODRIGUES et al, 2003) NAVARRO et al, 2018;RODRIGUES et al, 2003).…”

“…(2 a 50 nm) pode estar relacionada à eliminação de íons carbonatos (em forma de CO2), resultando na formação de crateras através de sua estrutura lamelar e no aparecimento dos poros (RODRIGUES et al, 2003).…”