Adsorption of Ni(II) on detoxified chromite ore processing residue using citrus peel as reductive mediator: Adsorbent preparation, kinetics, isotherm, and thermodynamics analysis

Yan, Chaoqun; Cheng, Zhiliang; Tian, Yijuan; Qiu, Facheng; Chang, Haixing; Li, Shuo; Cai, Yuhua; Quan, Xuejun

doi:10.1016/j.jclepro.2021.128209

Cited by 27 publications

(9 citation statements)

References 62 publications

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“…The Mo‐Fe/SiO 2 catalyst has the lowest catalytic activity, a methanol conversion rate of 21.9%, and DMM selectivity of only 8.3%. The order of catalytic activity of the five catalysts is: Mo‐Fe/HZSM‐5 (80) > Mo‐Fe/HZSM‐5 40 >Mo‐Fe/ Al 2 O 3 >Mo‐Fe/Y zeolite>Mo‐Fe/SiO 2 . This result is consistent with the results of the activation energy experiment.…”

Section: Resultsmentioning

confidence: 97%

“…According to the parameters in Table 3, we can calculate the thermodynamic data of each reaction in the process at 298.15 K. Calculated as follows 40 :

∆_{r} H_{m, 298.15}^{normalθ} = \sum_{i} V_{i} ∆_{f} H_{m, 298.15}^{normalθ} (i),

∆_{r} S_{m, 298.15}^{normalθ} = \sum_{i} V_{i} ∆_{f} S_{m, 298.15}^{normalθ} (i),

∆_{r} G_{m, 298.15}^{normalθ} = ∆_{r} H_{m, 298.15}^{normalθ} - 298.15 \times ∆_{r} S_{m, 298.15}^{normalθ},

K^{θ} = \exp [\frac{{- italic∆}_{r} G^{θ}}{RT}] .

The thermodynamic results of Reactions at 298.15 K, calculated according to the above formula, are shown in Table 4. It shows that the standard molar formation enthalpies (Δ r H θ m ) of the six reactions are all negative, which indicates that the reactions involved in the one‐step methanol process are all exothermic 42 .…”

Section: Resultsmentioning

confidence: 99%

“…In Table 7, the methanol conversion rate of the Mo‐Fe/HZSM‐5 (80) catalyst is 22.6% and the target product DMM selectivity reaches 68.2%, which is the highest among the five catalysts. The Mo‐Fe/HZSM‐5 40 catalyst had the highest methanol conversion, but the DMM selectivity was only 58.0%. The Mo‐Fe/Y zeolite catalyst had a high methylal selectivity of 70.8%, but the lowest methanol conversion of 17.2%.…”

Section: Resultsmentioning

confidence: 99%

“…In As shown in Figure 5, the Mo-Fe/HZSM-5 (80) activation energy was Ea = 69.84 kJÁmol À1 , which is the lowest activation energy among the five catalysts. The Mo-Fe/ HZSM-5 (40) has lower activation energy, while Mo-Fe/ SiO 2 has an activation energy Ea = 98.27 kJÁmol À1 , which is the highest among the five catalysts. The activation energy is the minimum energy required for a chemical reaction to occur.…”

Section: Analysis Of Kinetics and Product Distributionmentioning

confidence: 92%

“…This parameter is referenced to the research values of Prof. Wang Shufang's group at Hebei University of Technology. 37 According to the parameters in Table 3, we can calculate the thermodynamic data of each reaction in the process at 298.15 K. Calculated as follows 40 :…”

Section: Thermodynamic Analysis Calculationmentioning

confidence: 99%

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One‐step synthesis of methylal via methanol oxidation: Reaction kinetics, mechanism, thermodynamics, and product analysis

Yuan

Sun

Tian

et al. 2022

Intl J of Energy Research

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Summary The recent abundance of methanol has made it an attractive raw material for chemical synthesis. This study conducts a thermodynamic analysis of the main and side reactions in a system where methanol is oxidized to methylal. A relationship between the thermodynamics and product distribution of this system is proposed. By studying the effect of reaction temperature on the catalytic activity of a Mo‐Fe/HZSM‐5 (80‐80) catalyst, the relationship between thermodynamic parameters and product distribution was further verified. Kinetic analysis of the one‐step process shows that a lower activation energy is one of the reasons for the higher catalytic activity of the iron‐molybdenum‐based bifunctional catalyst. Accordingly, it is proposed that all main and side reactions in this process are driven by two chemical adsorption reactions. The first occurs at active sites of iron and molybdenum oxidation on the catalyst surface. The adsorbed methanol and O2 obtain hydroxyl and methoxy groups linked to the iron molybdate. Subsequently, desorbed formaldehyde and methanol undergo a second chemical adsorption on the acidic active centres of the catalyst with surface carbonyl and hydroxyl groups, respectively. Formaldehyde and the adsorbed methoxy group are catalysed by the acidic sites to generate intermediates similar to the methoxy and methylene group structures. This study provides complete information on the thermodynamics, kinetics, and reaction mechanism of a one‐step process of producing methylal from methanol, thereby allowing optimization of this process.

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Section: Resultsmentioning

confidence: 97%

“…According to the parameters in Table 3, we can calculate the thermodynamic data of each reaction in the process at 298.15 K. Calculated as follows 40 :