scholarly journals Development of a thermally stable Pt catalyst by redispersion between CeO2 and Al2O3

RSC Advances ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 7015-7024
Author(s):  
Li Lan ◽  
Xin Huang ◽  
Weiqi Zhou ◽  
Hongmei Li ◽  
Junhuai Xiang ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Pt Catalyst ◽  
Thermally Stable ◽  
Hydrothermal Aging

Ce/Pt/Al undergoes redispersion of Pt upon hydrothermal aging, resulting in higher dispersion and consequently superior three-way catalytic performance of Ce/Pt/Al-a.

scholarly journals High-throughput computational-experimental screening protocol for the discovery of bimetallic catalysts

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Byung Chul Yeo ◽  
Hyunji Nam ◽  
Hyobin Nam ◽  
Min-Cheol Kim ◽  
Hong Woo Lee ◽  
...  
Keyword(s):  
High Throughput ◽  
Bimetallic Catalysts ◽  
High Throughput Screening ◽  
Direct Synthesis ◽  
Catalytic Performance ◽  
Platinum Group Metals ◽  
Pt Catalyst ◽  
Electronic Density ◽  
Bimetallic Alloy ◽  
Screening Protocol

AbstractTo accelerate the discovery of materials through computations and experiments, a well-established protocol closely bridging these methods is required. We introduce a high-throughput screening protocol for the discovery of bimetallic catalysts that replace palladium (Pd), where the similarities in the electronic density of states patterns were employed as a screening descriptor. Using first-principles calculations, we screened 4350 bimetallic alloy structures and proposed eight candidates expected to have catalytic performance comparable to that of Pd. Our experiments demonstrate that four bimetallic catalysts indeed exhibit catalytic properties comparable to those of Pd. Moreover, we discover a bimetallic (Ni-Pt) catalyst that has not yet been reported for H2O2 direct synthesis. In particular, Ni61Pt39 outperforms the prototypical Pd catalyst for the chemical reaction and exhibits a 9.5-fold enhancement in cost-normalized productivity. This protocol provides an opportunity for the catalyst discovery for the replacement or reduction in the use of the platinum-group metals.

Study of the CA-treated ZSM-22 zeolite with enhanced catalytic performance in the hydroisomerization of long-chain n-dodecane

2021 ◽  
Author(s):  
Liwen He ◽  
Wenqian Fu ◽  
Leyi Li ◽  
Yuxian Huang ◽  
Liyu Chen ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Molar Concentration ◽  
Pt Catalyst ◽  
Long Chain

In this study, Pt catalyst on series of ZSM-22 zeolites treated by citric (CA) solution with different molar concentration (Pt/ZSM-22-CA-x, x=0,1, 2, and 3) was prepared, and evaluated in the...

scholarly journals Tuning the Reaction Selectivity over MgAl Spinel-Supported Pt Catalyst in Furfuryl Alcohol Conversion to Pentanediols

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 415
Author(s):  
Xinsheng Li ◽  
Jifeng Pang ◽  
Jingcai Zhang ◽  
Xianquan Li ◽  
Yu Jiang ◽  
...  
Keyword(s):  
Furfuryl Alcohol ◽  
Pt Nanoparticles ◽  
Catalytic Performance ◽  
Major Product ◽  
Pt Catalyst ◽  
Reaction Products ◽  
Strong Base ◽  
Reaction Selectivity ◽  
Supported Pt Catalysts ◽  
Alcohol Conversion

Catalytic conversion of biomass-derived feedstock to high-value chemicals is of remarkable significance for alleviating dependence on fossil energy resources. MgAl spinel-supported Pt catalysts were prepared and used in furfuryl alcohol conversion. The approaches to tune the reaction selectivity toward pentanediols (PeDs) were investigated and the catalytic performance was correlated to the catalysts’ physicochemical properties based on comprehensive characterizations. It was found that 1–8 wt% Pt was highly dispersed on the MgAl2O4 support as nanoparticles with small sizes of 1–3 nm. The reaction selectivity did not show dependence on the size of Pt nanoparticles. Introducing LiOH onto the support effectively steered the reaction products toward the PeDs at the expense of tetrahydrofurfuryl alcohol (THFA) selectivity. Meanwhile, the major product in PeDs was shifted from 1,5-PeD to 1,2-PeD. The reasons for the PeDs selectivity enhancement were attributed to the generation of a large number of medium-strong base sites on the Li-modified Pt catalyst. The reaction temperature is another effective factor to tune the reaction selectivity. At 230 °C, PeDs selectivity was enhanced to 77.4% with a 1,2-PeD to 1,5-PeD ratio of 3.7 over 4Pt/10Li/MgAl2O4. The Pt/Li/MgAl2O4 catalyst was robust to be reused five times without deactivation.

scholarly journals Magnetic Fe2O3–SiO2–MeO2–Pt (Me = Ti, Sn, Ce) as Catalysts for the Selective Hydrogenation of Cinnamaldehyde. Effect of the Nature of the Metal Oxide

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 413 ◽  
Author(s):  
Robinson Dinamarca ◽  
Rodrigo Espinoza-González ◽  
Cristian Campos ◽  
Gina Pecchi
Keyword(s):  
Metal Oxide ◽  
Continuous Production ◽  
Catalytic Performance ◽  
Structure Design ◽  
Pt Catalyst ◽  
Full Characterization ◽  
Magnetic Cores ◽  
Homogeneous Core ◽  
The Mean ◽  
Nanoparticle Sizes

The type of metal oxide affects the activity and selectivity of Fe2O3–SiO2–MeO2–Pt (Me = Ti, Sn, Ce) catalysts on the hydrogenation of cinnamaldehyde. The double shell structure design is thought to protect the magnetic Fe2O3 cores, and also act as a platform for depositing a second shell of TiO2, SnO2 or CeO2 metal oxide. To obtain a homogeneous metallic dispersion, the incorporation of 5 wt % of Pt was carried out over Fe2O3–SiO2–MeO2 (Me = Ti, Sn, Ce) structures modified with (3-aminopropyl)triethoxysilane by successive impregnation-reduction cycles. The full characterization by HR-TEM, STEM-EDX, XRD, N2 adsorption isotherm at −196 °C, TPR-H2 and VSM of the catalysts indicates that homogeneous core-shell structures with controlled nano-sized magnetic cores, multi-shells and metallic Pt were obtained. The nature of the metal oxide affects the Pt nanoparticle sizes where the mean Pt diameter is in the order: –TiO2–Pt > –SnO2–Pt > –CeO2–Pt. Among the catalysts studied, –CeO2–Pt had the best catalytic performance, reaching the maximum of conversion at 240 min. of reaction without producing hydrocinnamaldehyde (HCAL). It also showed a plot volcano type for the production of cinnamic alcohol (COL), with 3-phenyl-1-propanol (HCOL) as a main product. The –SnO2–Pt catalyst showed a poor catalytic performance attributable to the Pt clusters’ occlusion in the irregular surface of the –SnO2. Finally, the –TiO2–Pt catalyst showed a continuous production of COL with a 100% conversion and 65% selectivity at 600 min of reaction.

A facile Pt catalyst regeneration process significantly improves the catalytic activity of Pt–organic composites for the O2 reduction reaction

2015 ◽  
Vol 51 (60) ◽  
pp. 12052-12055 ◽  
Author(s):  
Jing-Fang Huang ◽  
Wen-Yu Chen
Keyword(s):  
Catalytic Activity ◽  
Size Effect ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
Pt Catalyst ◽  
O2 Reduction ◽  
Organic Composites ◽  
Acidic Conditions ◽  
Nano Size ◽  
Complexation Ability

Combination of the “nano-size” effect and Cl− complexation ability causes massive electrodissolution of Pt under acidic conditions to promote the regeneration of Pt–organic composites and to significantly improve the catalytic performance of the O2 reduction reaction.

scholarly journals Increasing Al-Pair Abundance in SSZ-13 Zeolite via Zeolite Synthesis in the Presence of Alkaline Earth Metal Hydroxide Produces Hydro-Thermally Stable Cobalt and Pd-SSZ-13 Materials for Pollutant Abatement Applications

2021 ◽  
Author(s):  
Konstantin Khivantsev ◽  
Miroslaw A. Derewinski ◽  
Nicholas R. Jaegers ◽  
Daria Boglaienko ◽  
Xavier Isidro Pereira Hernandez ◽  
...  
Keyword(s):  
Alkaline Earth ◽  
Air Flow ◽  
Earth Metal ◽  
Ambient Air ◽  
Critical Issue ◽  
Alkaline Earth Metal ◽  
Thermally Stable ◽  
Hydrothermal Aging ◽  
Nox Adsorber ◽  
Nox Adsorption

<div> <p>We show that replacing alkaline (NaOH) for alkaline-earth metal (Sr(OH)<sub>2 </sub>as an example) in the synthesis of SSZ-13 zeolite with Si/Al~10 produces SSZ-13 zeolite material with novel, advantageous properties. Its NH<sub>4</sub>-form ion-exchanges higher amount of Co(II) ions than the conventional one: this is the consequence of increased number of Al pairs in the structure induced by the +2 charge of Sr(II) cations in the synthesis gel that force two charge-compensating AlO<sub>4</sub><sup>-</sup> motives to be closer together. We characterize the +2 state of Co(II) ions in these materials with infra-red spectroscopy and XANES measurements. They can be used for NOx pollutant adsorption from ambient air: the ones derived from SSZ-13 with higher Al pair content contain more cobalt(II) and thus, perform better as ambient-air NOx adsorbers before reaching full saturation capacity. Notably, Co(II)/SSZ-13 material with increased number of Al pairs is significantly more hydrothermally stable than its NaOH-derived analogue. Loading 1.7 wt% Pd into Co-SSZ-13 synthesized in the presence of Sr(II) produces a passive NOx adsorber (PNA) material that can be used for NOx adsorption from simulated diesel engine exhaust. The critical issue for these applications is hydrothermal stability of Pd-zeolites. Pd/SSZ-13 synthesized in NaOH media loses most of its PNA capacity after ~800 ⁰C hydrothermal aging in the flow of air and steam (10 hours in 10% H<sub>2</sub>O/air flow). The 1.7 wt% Pd/Co/SSZ-13 material with Si/Al ~10 does not lose its PNA capacity after extremely harsh aging at 850 and 900 ⁰C (10 hours in 10% H<sub>2</sub>O/Air flow) and loses only ~55% capacity after hydrothermal aging at 930 ⁰C. It shows considerably enhanced stability compared with previous record for Pd/FER, Pd/SSZ-39 and Pd/BEA materials that could survive hydrothermal aging no higher than 820 ⁰C. We herein reveal a new, simple, and scalable strategy for making remarkably (hydro)thermally stable metal-zeolite materials/catalysts with a number of useful applications. </p> </div>

scholarly journals Investigation of the hydrothermal aging of an Mn-based mullite SmMn2O5 catalyst of NO oxidation

RSC Advances ◽  
2017 ◽  
Vol 7 (77) ◽  
pp. 49091-49096 ◽  
Author(s):  
Lina Xue ◽  
Ka Xiong ◽  
Haijun Chen ◽  
Kyeongjae Cho ◽  
Weichao Wang
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Catalytic Performance ◽  
No Oxidation ◽  
Hydrothermal Aging

The decrease in the catalytic performance for NO oxidation of the Mn-based mullite SmMn2O5 after being subjected to hydrothermal aging was mainly caused by an ∼3-fold decrease in its specific surface area (BET).

scholarly journals Increasing Al-Pair Abundance in SSZ-13 Zeolite via Zeolite Synthesis in the Presence of Alkaline Earth Metal Hydroxide Produces Hydro-Thermally Stable Cobalt and Pd-SSZ-13 Materials for Pollutant Abatement Applications

2021 ◽  
Author(s):  
Konstantin Khivantsev ◽  
Miroslaw A. Derewinski ◽  
Nicholas R. Jaegers ◽  
Daria Boglaienko ◽  
Xavier Isidro Pereira Hernandez ◽  
...  
Keyword(s):  
Alkaline Earth ◽  
Air Flow ◽  
Earth Metal ◽  
Ambient Air ◽  
Critical Issue ◽  
Alkaline Earth Metal ◽  
Thermally Stable ◽  
Hydrothermal Aging ◽  
Nox Adsorber ◽  
Nox Adsorption

<div> <p>We show that replacing alkaline (NaOH) for alkaline-earth metal (Sr(OH)<sub>2 </sub>as an example) in the synthesis of SSZ-13 zeolite with Si/Al~10 produces SSZ-13 zeolite material with novel, advantageous properties. Its NH<sub>4</sub>-form ion-exchanges higher amount of Co(II) ions than the conventional one: this is the consequence of increased number of Al pairs in the structure induced by the +2 charge of Sr(II) cations in the synthesis gel that force two charge-compensating AlO<sub>4</sub><sup>-</sup> motives to be closer together. We characterize the +2 state of Co(II) ions in these materials with infra-red spectroscopy and XANES measurements. They can be used for NOx pollutant adsorption from ambient air: the ones derived from SSZ-13 with higher Al pair content contain more cobalt(II) and thus, perform better as ambient-air NOx adsorbers before reaching full saturation capacity. Notably, Co(II)/SSZ-13 material with increased number of Al pairs is significantly more hydrothermally stable than its NaOH-derived analogue. Loading 1.7 wt% Pd into Co-SSZ-13 synthesized in the presence of Sr(II) produces a passive NOx adsorber (PNA) material that can be used for NOx adsorption from simulated diesel engine exhaust. The critical issue for these applications is hydrothermal stability of Pd-zeolites. Pd/SSZ-13 synthesized in NaOH media loses most of its PNA capacity after ~800 ⁰C hydrothermal aging in the flow of air and steam (10 hours in 10% H<sub>2</sub>O/air flow). The 1.7 wt% Pd/Co/SSZ-13 material with Si/Al ~10 does not lose its PNA capacity after extremely harsh aging at 850 and 900 ⁰C (10 hours in 10% H<sub>2</sub>O/Air flow) and loses only ~55% capacity after hydrothermal aging at 930 ⁰C. It shows considerably enhanced stability compared with previous record for Pd/FER, Pd/SSZ-39 and Pd/BEA materials that could survive hydrothermal aging no higher than 820 ⁰C. We herein reveal a new, simple, and scalable strategy for making remarkably (hydro)thermally stable metal-zeolite materials/catalysts with a number of useful applications. </p> </div>

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