scispace - formally typeset
Search or ask a question
Author

Jose A. Hernandez Gaitan

Bio: Jose A. Hernandez Gaitan is an academic researcher. The author has contributed to research in topics: Zeolite & Supercritical fluid. The author has an hindex of 1, co-authored 3 publications receiving 4 citations.

Papers
More filters
Journal ArticleDOI
22 Sep 2022
TL;DR: In this article , the authors proposed a new method to synthesize various zeolite•nanosheets from the same amorphous aluminosilicate NSs (AAS•NSs) as a universal precursor.
Abstract: Abstract Zeolites catalyze some reactions in their molecular‐sized pores, but large molecules can react only on their external surface. Zeolite‐nanosheets (NSs) have been developed as catalysts for large molecules. The previously reported methods to synthesize zeolite‐NSs are specialized for each zeolite type. Here we propose a new method to synthesize various zeolite‐NSs from the same amorphous aluminosilicate NSs (AAS‐NSs) as a universal precursor. We successfully synthesized the unprecedented AAS‐NSs in the hydrophilic space of the stable hyperswollen lyotropic lamellar (HL) phase. The four zeolite types could be obtained from the single‐species AAS‐NSs. These results imply that this method enables us to synthesize almost all types of zeolite‐NSs. Moreover, the synthesized CHA‐NSs have great potential for various applications because of their thickness and large external surface area.

3 citations

29 May 2023
TL;DR: In this paper , restricted Falconer distance problems are introduced, which lie in between the classical version and its pinned variant, and they are shown to have non-empty interior if the diagonal distance set has a nonempty interior.
Abstract: We introduce a new class of Falconer distance problems, which we call restricted Falconer distance problems, that lie in between the classical version and its pinned variant. A particular model we study is the diagonal distance set $$\Delta^{diag}(E)= \{ \,|(x,x)-(y_1,y_2)| \, :\, x,\,y_1,\,y_2\, \in E\, \}$$ which we show has non-empty interior if $\dim(E)>\frac{2d+1}{3}$. Standard pinned variants of the Falconer distance problem either can not guarantee a pin on the diagonal or yield worse dimensional thresholds. A key tool for our result is an $L^p$ improving estimate for the bilinear spherical averaging operator with decay on frequency scales.

1 citations

Journal ArticleDOI
TL;DR: In this article , the transalkylation reaction kinetics of 4-propylphenol (ppp) and supercritical benzene (11.0 MPa) over H-MFI-type zeolites, using different particle size and Si/Al ratios, in the temperature range of 623 K − 673 K, was studied in a fixed bed reactor.

Cited by
More filters
Journal ArticleDOI
22 Sep 2022
TL;DR: In this article , the authors proposed a new method to synthesize various zeolite•nanosheets from the same amorphous aluminosilicate NSs (AAS•NSs) as a universal precursor.
Abstract: Abstract Zeolites catalyze some reactions in their molecular‐sized pores, but large molecules can react only on their external surface. Zeolite‐nanosheets (NSs) have been developed as catalysts for large molecules. The previously reported methods to synthesize zeolite‐NSs are specialized for each zeolite type. Here we propose a new method to synthesize various zeolite‐NSs from the same amorphous aluminosilicate NSs (AAS‐NSs) as a universal precursor. We successfully synthesized the unprecedented AAS‐NSs in the hydrophilic space of the stable hyperswollen lyotropic lamellar (HL) phase. The four zeolite types could be obtained from the single‐species AAS‐NSs. These results imply that this method enables us to synthesize almost all types of zeolite‐NSs. Moreover, the synthesized CHA‐NSs have great potential for various applications because of their thickness and large external surface area.

3 citations

08 Jun 2023
TL;DR: In this paper , the authors considered a variant of the Falconer distance problem, where the Hausdorff dimension of the set is larger than the square root of the square norm of the Euclidean distance.
Abstract: In this paper we study the following variant of the Falconer distance problem. Let $E$ be a compact subset of $\mathbb{R}^d$, $d \ge 1$, and define $$ \Box(E)=\left\{\sqrt{{|x-y|}^2+{|x-z|}^2}: x,y,z \in E,\, y eq z \right\}.$$ We shall prove using a variety of methods that if the Hausdorff dimension of $E$ is greater than $\frac{d}{2}+\frac{1}{4}$, then the Lebesgue measure of $\Box(E)$ is positive. This problem can be viewed as a singular variant of the classical Falconer distance problem because considering the diagonal $(x,x)$ in the definition of $\Box(E)$ poses interesting complications stemming from the fact that the set $\{(x,x): x \in E\}\subseteq \mathbb{R}^{2d}$ is much smaller than the sets for which the Falconer type results are typically established. We also prove a finite field variant of the Euclidean results for $\Box(E)$ and indicate both the similarities and the differences between the two settings.

1 citations

Journal ArticleDOI
TL;DR: In this paper , a modularized hydrogenation mode with hydrogen dissociation and substrate activation on different sites (e.g., Pt and Cu), where Pt nanoclusters are responsible for H2 dissociation, and Cu nanoparticles act as the active center for further substrate activation is presented.
Abstract: Designing optimal heterogeneous metal hydrogenation catalysts for biomass conversion with simultaneously high activity and selectivity is a significant but challenging topic. Herein, we report a modularized hydrogenation mode with hydrogen dissociation and substrate activation on different sites (e.g., Pt and Cu), where Pt nanoclusters are responsible for H2 dissociation and Cu nanoparticles act as the active center for further substrate activation. Specifically, TS-1 zeolite@mesoporous silica with a core–shell structure was fabricated, in which the Pt and Cu species are confined within micropores and mesopores, respectively. Such configurations allow facile dissociation of H2 on Pt sites, followed by the migration of spilled-over hydrogen atoms to the Cu sites where the adsorbed substrates are activated for catalytic hydrogenation. This synergy yields an efficient furfural hydrogenation system with a high turnover frequency (32.8 h–1) and a remarkable furfuryl alcohol selectivity (>99.6%). The modularizing strategy opens up an innovative pathway for fabrication of hydrogenation catalysts with outstanding activity and high selectivity.