A new reactivation method towards deactivation of honeycomb ceramic monolith supported cobalt–molybdenum–boron catalyst in hydrolysis of sodium borohydride

Zhuang, Da-Wei; Dai, Hongzhe; Zhong, Yujie; Sun, Lin; Wang, Ping

doi:10.1016/j.ijhydene.2015.05.177

Cited by 42 publications

(16 citation statements)

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“…Thus, a method such as encapsulation of Co NPs in carbon nanomaterials was proposed to prevent agglomeration and leaching of cobalt. [ 61 ] There is no deactivation of ZIF‐8 (NaCl) during the charging of NaBH 4 without the need for separation or activation process (Figure 7).…”

Section: Resultsmentioning

confidence: 99%

Salts Induced Formation of Hierarchical Porous ZIF‐8 and Their Applications for CO₂ Sorption and Hydrogen Generation via NaBH₄ Hydrolysis

Abdelhamid

2020

Macro Chemistry & Physics

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Despite the great potential of two different pore regimes (hierarchical porous (HP) structure), HP‐zeolitic imidazolate frameworks‐8 (HPZIF‐8) can be efficient catalysts for hydrogen generation via hydride hydrolysis, and as adsorbents for CO2 gas adsorption. Herein, HPZIF‐8, and leaf‐like ZIF (ZIF‐L) are synthesized via a simple and environmentally friendly procedure using layered hydroxide nitrate of zinc (Z5HN) as a metal source and simple inorganic salt as a modulator. Z5HN nanosheets undergo topotactic transformation to simonkolleite (Zn5(OH)8Cl2·H2O) that can be converted to the pure phase of HPZIF‐8. The concentration of the salts tunes the textural properties of the final product. Applications of HPZIF‐8 and ZIF‐L for CO2 sorption exhibit excellent adsorption properties with increases of 25% due to the presence of cations in the frameworks. ZIF‐8 shows exceptional high catalytic activity for hydrogen generation via the hydrolysis of sodium borohydride. The simple synthesis of ZIF‐8 as well as their good performance as adsorbent and catalyst ensure the potential for industrial and commercial uses.

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Section: Resultsmentioning

confidence: 99%

Salts Induced Formation of Hierarchical Porous ZIF‐8 and Their Applications for CO₂ Sorption and Hydrogen Generation via NaBH₄ Hydrolysis

Abdelhamid

2020

Macro Chemistry & Physics

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“…In view of this, ex-situ washing with diluted acid was proposed as an efficient method to eliminate this B-O layer (basic in nature) and by this recover the catalyst activity [11][12]. Low temperature calcination was also reported as an efficient method to eliminate water from this layer to recover the catalysts original activity [14]. Alternatively, cobalt can be combined with other metals in order to reduce its sensitivity to borates adsorption.…”

Section: Introductionmentioning

confidence: 99%

“…After catalyst drying (State IV), those cobalt hydroxides and oxyhydroxides, which remained on the surface, may lose water molecules. This could influence in the activity in the following run, which effect was not studied in this work[14]. At the beginning of the second run, sodium borohydride reduces catalyst the surface again, forming the Co x B active phase (State V).…”

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confidence: 95%

The role of cobalt hydroxide in deactivation of thin film Co-based catalysts for sodium borohydride hydrolysis

Paladini

Arzac

Godinho

et al. 2017

Applied Catalysis B: Environmental

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Deactivation of a Co catalyst prepared as thin film by magnetron sputtering was studied for the sodium borohydride (SB) hydrolysis reaction under different conditions. Under high SB concentration in single run experiments, the formation of a B-O passivating layer was observed after 1.5 and 24 h use. This layer was not responsible for the catalyst deactivation. Instead, a peeling-off mechanism produced the loss of cobalt. This peeling-off mechanism was further studied in cycling experiments (14 cycles) under low SB concentrations. Ex-situ study of catalyst surface after use and solid reaction products (precipitates) was performed by X-Ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The presence of cobalt hydroxide and oxyhydroxide was detected as major components on the catalyst surface after use and as precipitates in the supernatant solutions after washing. Cobalt borate, cobalt carbonate and oxycarbonate *Revised Manuscript Click here to view linked References were also formed but in lesser amounts. These oxidized cobalt species were formed and further detached from the catalyst at the end of the reaction and/or during catalyst washing by decomposition of the unstable in-situ formed cobalt boride. Leaching of cobalt soluble species was negligible. Thin film mechanical detachment was also found but in a smaller extent. To study the influence of catalyst composition on deactivation processes, cycling experiments were performed with CoB and Co-C catalysts, also prepared as thin films. We found that the deactivation mechanism proposed by us for the pure Co catalyst also occurred for a different pure Co (prepared at higher pressure) and the CoB and Co-C samples in our experimental conditions.

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“…9b does not show the contribution of surface boron. This result is very important, because deactivation processes are usually attributed to the presence of borates 13 , 14 , 30 , 31 . In our conditions, neither activation nor deactivation can be conclusively explained by the incorporation of boron on catalyst surface.…”

Section: Resultsmentioning

confidence: 99%

Strong activation effect on a Ru-Co-C thin film catalyst for the hydrolysis of sodium borohydride

Arzac

Paladini

Godinho

et al. 2018

Sci Rep

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In this work, we prepared a series of Ni foam supported Ru-Co, Ru-Co-B and Ru-Co-C catalysts in the form of columnar thin films by magnetron sputtering for the hydrolysis of sodium borohydride. We studied the activity and durability upon cycling. We found a strong activation effect for the Ru-Co-C sample which was the highest ever reported. This catalyst reached in the second cycle an activity 5 times higher than the initial (maximum activity 9310 ml.min−1.gCoRu−1 at 25 °C). Catalytic studies and characterization of the fresh and used samples permitted to attribute the strong activation effect to the following factors: (i) small column width and amorphous character (ii) the presence of Ru and (iii) dry state before each cycle. The presence of boron in the initial composition is detrimental to the durability. Our studies point out to the idea that after the first cycle the activity is controlled by surface Ru, which is the most active of the two metals. Apart from the activation effect, we found that catalysts deactivated in further cycles. We ascribed this effect to the loss of cobalt in the form of hydroxides, showing that deactivation was controlled by the chemistry of Co, the major surface metal component of the alloy. Alloying with Ru is beneficial for the activity but not for the durability, and this should be improved.

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A new reactivation method towards deactivation of honeycomb ceramic monolith supported cobalt–molybdenum–boron catalyst in hydrolysis of sodium borohydride

Cited by 42 publications

References 44 publications

Salts Induced Formation of Hierarchical Porous ZIF‐8 and Their Applications for CO₂ Sorption and Hydrogen Generation via NaBH₄ Hydrolysis

Salts Induced Formation of Hierarchical Porous ZIF‐8 and Their Applications for CO₂ Sorption and Hydrogen Generation via NaBH₄ Hydrolysis

The role of cobalt hydroxide in deactivation of thin film Co-based catalysts for sodium borohydride hydrolysis

Strong activation effect on a Ru-Co-C thin film catalyst for the hydrolysis of sodium borohydride

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A new reactivation method towards deactivation of honeycomb ceramic monolith supported cobalt–molybdenum–boron catalyst in hydrolysis of sodium borohydride

Cited by 42 publications

References 44 publications

Salts Induced Formation of Hierarchical Porous ZIF‐8 and Their Applications for CO2 Sorption and Hydrogen Generation via NaBH4 Hydrolysis

Salts Induced Formation of Hierarchical Porous ZIF‐8 and Their Applications for CO2 Sorption and Hydrogen Generation via NaBH4 Hydrolysis

The role of cobalt hydroxide in deactivation of thin film Co-based catalysts for sodium borohydride hydrolysis

Strong activation effect on a Ru-Co-C thin film catalyst for the hydrolysis of sodium borohydride

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Salts Induced Formation of Hierarchical Porous ZIF‐8 and Their Applications for CO₂ Sorption and Hydrogen Generation via NaBH₄ Hydrolysis

Salts Induced Formation of Hierarchical Porous ZIF‐8 and Their Applications for CO₂ Sorption and Hydrogen Generation via NaBH₄ Hydrolysis