Examinando por Autor "Serrano, David pedro"

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Catalytic upgrading of a model polyethylene pyrolysis oil by hydroconversion over Ni-containing hierarchical Beta zeolites with tailored acidity
(Elsevier, 2023-10-05) Briones, Laura; Cordero, Adrian; Alonso-Doncel, Mara; Serrano, David pedro; Escola, José María
Valorization of waste polyolefins by a sequential combination of thermal pyrolysis and catalytic hydroconversion over a bifunctional metal/acid catalyst (e.g. zeolite) is an efficient route to produce transportation fuels. However, the zeolite strong acidity typically causes extensive cracking and loss of liquid fuels. In this work, mild dealumination with oxalic acid of a hierarchical Beta zeolite was used to achieve Ni 7 %/h-Beta catalysts with Si/Al ratios within the 25 – 130 range. These catalysts were tested in the hydroconversion of a model mixture of LDPE thermal pyrolysis product (1-dodecene/n-dodecane, 50/50 w/w). The highest share of liquid fuels (~ 90 %) was achieved over 7% Ni/h-Beta (Si/Al = 130). Besides, due to its high accessibility and tailored acidity, the product contained a meaningful amount of isoparaffins (12 %) and a negligible content of olefins (< 3.5 %). Thus, this catalyst holds promise for plastic waste hydroconversion towards transportation fuels.
One-pot synthesis of cyclohexylphenol via isopropyl-assited phenol conversion using the tandem system raney Nickel plus hierarchical Beta zeolite
(Royal Society of Chemistry, 2022-11-07) García-Minguillán, Alba María; Briones, laura; Alonso-Doncel, Mara; Cejka, Jiri; Serrano, David pedro; Botas, juan ángel; Escola, José María
Cyclohexylphenols are valuable intermediate chemicals applied in the manufacture of dyes, resins, and pharmaceutical drugs. However, they are synthesized using raw chemicals derived from fossil fuels rather than sustainable sources (e.g., lignin-derived phenol). In this article, we report a one-pot synthesis of cyclohexylphenols via phenol-assisted conversion with isopropyl alcohol over the tandem catalytic system formed by Raney Nickel plus hierarchical Beta zeolite. Over this tandem catalytic system, cyclohexylphenols were synthesized with remarkable selectivity (~ 70%) at high conversion rates (64%) after 1 h of reaction at 150º C. In contrast, higher temperatures (175 ºC) were required to obtain alkylphenols over Al-SBA-15 catalyst, which is highly accessible thanks to its uniform mesoporous structure, albeit with weaker Lewis acid sites. Additionally, selectivity to cyclohexylphenols over Al-SBA-15 was far lower (19%) than over hierarchical Beta zeolite, and cresols were instead the most abundant alkylphenol (26%). Therefore, the combination of suitable accessibility and Brønsted acidity of hierarchical Beta with the hydrogenating ability of Raney Ni through catalytic hydrogen transfer from isopropyl alcohol drive the selectivity of this tandem system towards the production of cyclohexylphenols.