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Article

A Highly Efficient Catalytic Co-Combustion of Aromatic and Oxygenated Volatile Organic Compounds (VOCs) via H2-Driven Onsite Heating

by
Sehrish Munsif
1,2,†,
Lutf Ullah
1,2,†,
Long Cao
1,2,
Palle Ramana Murthy
1,
Jing-Cai Zhang
1 and
Wei-Zhen Li
1,2,*
1
CAS Key Laboratory of Science and Technology on Applied Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
2
University of Chinese Academy of Sciences, Beijing 100049, China
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work
Catalysts 2024, 14(10), 729; https://doi.org/10.3390/catal14100729
Submission received: 25 September 2024 / Revised: 11 October 2024 / Accepted: 15 October 2024 / Published: 18 October 2024
(This article belongs to the Section Environmental Catalysis)
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Abstract

:
Catalytic combustion, a highly efficient technique for reducing volatile organic compounds (VOCs), is the focus of this study. We investigate the improved catalytic efficiency of the physical mixing of nanosized Pt and atomically dispersed Co, supported on Al2O3 catalysts (Pt-Co)/Al2O3 (PM) for the catalytic combustion of VOCs. The catalyst efficiency is evaluated for the hydrogen-assisted catalytic oxidation of various VOCs, including aromatic and oxygenated VOCs such as benzene, toluene, methanol, and formic acid. Our study aims to understand the impact of hydrogen incorporation on the combustion process of various VOCs. The findings of this work underscore the potential of hydrogen-assisted catalytic ignition, which can achieve ignition at ambient temperature, a significant departure from conventional electric heating that typically requires additional energy to raise the temperature. Various characterization techniques, such as BET, STEM, and XRD, are employed to assess the structure–activity relationship of the catalyst. The optimal hydrogen concentration for complete VOC conversion is 3%. Notably, even at a lower hydrogen concentration of 2%, benzene and methanol reach an ideal ignition temperature of over 500 °C when introduced into the physically mixed catalyst. This study highlights the significant potential of hydrogen-assisted catalytic combustion, inspiring further research and offering a promising method to reduce VOCs effectively.

1. Introduction

Volatile organic compounds (VOCs) are prevalent pollutants commonly emitted by automotive exhausts and chemical or petrochemical industries. VOCs are hazardous substances that pose significant risks to human health and the environment [1,2,3,4]. Various techniques, such as adsorption, condensation, thermal oxidation, biodegradation, and catalytic thermal oxidation, have eliminated VOCs and reduced environmental pollution [5,6]. Several limitations related to the current technologies include safety concerns, large energy consumption, complex systems, high prices, and slow degradation rates [7,8,9]. Catalytic combustion is a key technology for removing VOCs due to its high combustion efficiency and relatively low need for auxiliary fuel [10]. However, conventional catalytic oxidation frequently necessitates higher temperatures, which increases the energy consumed and the hazards to safety [11,12,13]. As a result, there is a growing interest in developing catalytic oxidation processes that can achieve VOC degradation at low temperatures or even at room temperature.
The development of catalysts is the key factor in determining the success of low-temperature catalytic oxidation [14]. It has been proven that supported catalysts, particularly those that incorporate bimetallics as active components, exhibit outstanding performance in eliminating VOCs [15,16,17]. Nevertheless, these precious metals have been extensively investigated for the catalytic oxidation of VOCs. Still, due to the high cost and low availability, substituting the precious metals with cheaper sources is inevitable in developing mixed catalysts [18]. Cobalt (Co), owing to its electronic and geometric properties, can act as an excellent modifier for Pt-based catalysts in hydrogenation reactions, enhancing their catalytic efficiency compared to Pt monometallic catalysts. This modification optimizes the catalysts’ active sites and electron distribution, leading to improved performance in terms of the reaction rates and selectivity. Paul J. Dietrich et al. found that increasing Co in Pt-Co alloy catalysts strengthens Pt-Co interactions. Co enhances Pt’s performance by aiding CO removal, likely through accelerating the water–gas shift reaction or reducing CO binding on the catalyst’s surface, while the selectivity remains similar to monometallic Pt [19,20,21,22]. Activated alumina balls are cost-effective, high-surface-area supports that enhance precious metal dispersity, and are ideal for VOC degradation in catalytic systems [23]. The oxidation of VOCs is highly exothermic, often causing local “hot spots” near the catalytic sites, which can degrade the catalyst and lose the energy-saving benefit. According to the Arrhenius equation, upholding the precise temperature is crucial for complete VOC oxidation, and requires heat input in both thermal and catalytic processes. Therefore, improving the heating efficiency is essential for effective VOC elimination. Attaining stable and reliable ignition is crucial, with technologies like spark ignition, electric resistance heating, and hydrogen-assisted catalytic ignition [24]. Hydrogen-assisted catalytic ignition takes advantage of thermal and chemical effects, especially on catalyst surfaces like Pt supported on alumina. In this process, the key component controlling the ignition is the heat action of hydrogen [25]. The ignition temperature increases with H2 concentration, and the thermal effect of H2 is the most critical factor affecting the ignition [26]. In light of the fact that it is able to produce energy efficiently and sustainably, hydrogen stands out as a particularly advantageous fuel. The development of catalytic hydrogen combustion has made it possible to generate heat and energy without polluting the atmosphere with carbon-based emissions [27]. When co-fed with volatile organic compounds (VOCs) in the presence of precious/transition (mix) metal catalysts, catalytic hydrogen combustion occurs as onsite heating.
In this work, we have developed a (Pt-Co)/Al2O3 (PM) catalyst in which half of the costly Pt metal can be replaced with cheaper Co metal. We introduce a novel method that integrates the advantages of thermal incineration and catalytic oxidation by employing the hydrogen co-combustion on a (Pt-Co)/Al2O3 (PM) catalyst as a heating source, instead of traditional electric heating. It is feasible to commence the catalytic combustion of hydrogen using a catalyst composed of (Pt-Co) Al2O3 (PM) at ambient temperature. This will facilitate the heating of the catalyst bed to temperatures that enable the complete oxidation of both aromatic and oxygenated compounds such as benzene, toluene, methanol, and formic acid, while the concentration of hydrogen is below the low explosive limit of 4%.

2. Results

2.1. Structure Evolution of Catalyst

The (Pt-Co)/Al2O3 (PM) catalysts were designated as fresh and spent catalysts, respectively, before and after the catalytic oxidation of the VOCs utilizing H2 co-combustion heating and electric heating. The surface area of the fresh Pd/Al2O3 sample was measured to be 152.1 m2/g, while the spent sample maintained a surface area of 121.1 m2/g. This drop in surface area is consistent with other previous findings.
Figure 1 displays the XRD patterns for the fresh and spent (Pt-Co)/Al2O3 (PM) catalysts. The fresh sample does not show any peaks of Co or Pt; instead, it only displays the distinctive diffraction peaks of γ-Al2O3. This indicates that both metals were originally extensively dispersed over the Al2O3 substrate. However, an acute strong Pt diffraction peak at 2θ = 39.8° was observed in the spent catalyst. The lack of diffraction peaks for the Co species indicates that Co is in a high-dispersion state below the detection of XRD.
HAADF imaging and element mapping also addressed the initial dispersion of Pt and Co, and the structural evolution after performance assessment. Figure 2a illustrates the abundance of tiny Pt nanoparticles in the fresh (Pt-Co)/Al2O3 (PM) sample, represented in yellow circles. The homogeneous dispersion of Pt and Co nanoparticles in the fresh sample is seen in Figure 2b from the EDX mapping. However, we observed the clear aggregation in Figure 2c of Pt particles on the spent catalyst. The sintering of Pt nanoparticles was an unavoidable phenomenon observed in the conventional (Pt-Co)/Al2O3 (PM) catalyst, according to the results in the literature [28].
In scanning transmission electron microscopy (STEM) images, especially in high-angle annular dark-field (HAADF) mode, the white regions typically indicate areas of higher atomic number density. In HAADF STEM, heavier elements scatter electrons more intensely, resulting in brighter or whiter areas in the image. Therefore, the white regions are likely areas where heavier elements, such as platinum (Pt), are concentrated due to their higher atomic number and corresponding brightness. As for Co, it appears very sparse, suggesting a very high dispersion on the atomic scale. In our previous work reported in Ullah et al. (2024) [29,30], XPS data on Pd show minimal changes in oxidation state, and we observed the deep oxidation of VOCs to CO2 over Pd/Al2O3 without significant shifts in Pd’s oxidation state during hydrogen-assisted combustion. Similarly, we anticipate that Pt behaves in the same way in our study, as supported by our STEM results, which demonstrate the stability of Pt throughout the catalytic process. Existing research also indicates that hydrogen co-combustion, particularly below its lower explosive limit, can drive deep VOC oxidation to CO2 [29,30].

2.2. Catalytic Performance Test

The propensity of hydrogen to undergo ignition and establish a stable bed was examined at concentrations of 2%, 3%, and 4%. Upon ignition at ambient temperature, hydrogen fully oxidizes volatile organic molecules, establishing its catalytic capability to attain temperatures above 250 °C. This temperature is enough to completely convert toxic volatile organic compounds into CO2 and H2O. Upon initiating the reaction, hydrogen ignition at room temperature to abate VOCs raised the bed temperature over the threshold at which each VOC became fully incinerated. This led to a rapid 100% conversion in a few minutes. Figure 3 illustrates that introducing 2% H2 at ambient temperature led to a substantial elevation in the temperature of the catalyst bed, increasing from 20 °C to about 140 °C [31]. As H2 continued to flow, the temperature could be effectively maintained. Elevating the H2 content to 3% allowed for maintaining a temperature around 200 °C while further increasing the H2 content to 4%, maintaining the temperature at approximately 260 °C. Notably, even at H2 concentrations below the low explosive limit (4%), the catalyst bed could reach temperatures higher than the light-off temperatures for benzene and toluene. Such evidence underscores its significant capacity as a heating source, indicating its feasibility as a substitute for electronic heating systems [29].
The (Pt-Co)/Al2O3 (PM) catalyst is essential for promoting the oxidation of volatile organic compounds (VOCs) due to the synergistic effect between them. The experiment started with temperature-programmed reactions in an electric heating furnace to determine the light-off temperatures for several volatile organic compounds over the fresh PtCo/Al2O3 (PM) catalyst. The resulting light-off curves, which show trends in the elevation in the catalyst bed temperature and the generation of carbon dioxide (CO2), are shown in Figure 4 for the fresh catalyst.
Notably, in benzene, a distinct increase in the CO2 signal was detected at 42 min on stream, equivalent to a temperature of 234 °C. An analysis of the CO2 signal and temperatures reveals the exothermic character of benzene combustion and the heat-releasing features of the oxidation process. Higher furnace temperatures result in the stabilization of the CO2 signal at a temperature above 900 °C, suggesting complete benzene oxidation. The temperature increases linearly for a fresh catalyst with toluene, and a distinct CO2 peak appears at around 54 min. When the furnace temperature exceeds 620 °C, the CO2 signal stabilizes, indicating complete toluene oxidation. Regarding methanol, a distinctive CO2 peak appears 18 min later at 209 °C and is completely combusted around 350 °C. The CO2 peak of formic acid emerges 40 min later. However, the peak is not very sharp, most likely because of its low concentration.
The light-off curves for the spent catalyst, illustrating the trends in the increase in the catalyst bed temperature and the production of carbon dioxide (CO2), are presented in Figure 5. The behavior of the spent catalyst for benzene is the same as the fresh one regarding the exothermic peak and the light-off temperature. In the study of the light-off temperature of toluene, the CO2 peak appears 18 min earlier than with the fresh catalyst, likely due to the absorption of VOCs from previous tests on the catalyst surface. Additionally, the temperature peak is 40 °C lower than that of the fresh catalyst. The performance of the spent catalyst for methanol and formic acid was identical to that of the fresh catalyst in terms of the time and temperature at which CO2 appeared.
Figure 6a shows the change in profiles of the catalyst bed temperatures and CO2 signals with the co-feeding of H2 and VOCs. The underlying CO2 signals in the image above were obtained during the first 20 min of airflow at 1000 mL/min. For all four VOC tests, the temperatures recorded at 2% H2 were nearly 160 °C, which was exactly in line with the bed temperature in Figure 3. Upon adding 2% H2 to 10% VOC vapor, which is equivalent to a nominal benzene concentration of 0.99%, the temperatures in the benzene scenario immediately increased from 140 °C to 800 °C. At the same time, the CO2 signal intensities also increased to about 16 a.u. The reaction was halted when the benzene content was further raised because it became difficult to regulate the temperature, which rose to above 1000 °C in a matter of seconds. The observed rise in temperature, the generation of CO2, and the emergence of benzene vapors collectively indicate the co-combustion of benzene using the physically mixed catalyst. Figure 6b depicts the temporal changes in the catalyst bed temperature and CO2 production when the co-feeding H2 concentration was increased to 3%.
When 10% VOC vapor and 3% H2 were added, the temperatures for benzene oxidation increased to 900 °C. The maximum temperature gain in benzene prevents any more VOC insertion. Similarly, when the H2 concentration was increased to 4%, the bed temperature was about 260 °C. After a stable bed temperature, the initial 10% benzene insertion spiked and crossed 900 °C. When considered collectively, the (Pt-Co)/Al2O3 (PM) catalyst facilitates heating through hydrogen co-combustion, which initiates the oxidation of VOCs [32].
The toluene evolution profiles of the catalyst bed temperatures and CO2 signals during the co-feeding of H2 and VOCs are depicted in Figure 7a–c. An investigation was conducted to examine the impact of 2% hydrogen (H2) on toluene using concentrations of 10%, 20%, and 30% of VOCs. The temperature dropped from around 300 °C to 500 °C as VOCs were consistently added. Upon increasing the hydrogen concentration to 3%, a progressive increase in the CO2 signal was detected, accompanied by a temperature rise, reaching around 720 °C with the VOC concentrations varying from 10% to 30%. A comparable pattern was noted at a hydrogen concentration of 4%, and the maximum temperature exceeded 900 °C. The generation of CO2 and the temperature evolution curves for toluene differ greatly from benzene, potentially because of their significantly lower calorific values.
The initial study examined the effect of 2% hydrogen (H2) on methanol using VOC concentrations of 10%, 20%, and 30%. At 10% VOC concentration, the temperature rose from the catalyst bed temperature to 400 °C, and as VOCs were gradually added in steps, the temperature increased further to 512 °C. An increase in the hydrogen concentration to 3% resulted in a gradual rise in the CO2 signal, accompanied by a temperature increase, ultimately reaching around 650 °C as the concentrations of the volatile organic compounds (VOCs) ranged from 10% to 30%. A comparable trend was seen at a hydrogen concentration of 4%, with the highest temperature surpassing 780 °C (Figure 8).
For formic acid, with an initial 2% H2 and 10% VOC concentration, the temperature rose from the catalyst bed temperature to 250 °C, with a minimal increase probably attributed to its low calorific value. Gradually increasing the hydrogen concentration to 3% resulted in a progressive increase in the CO2 signal, accompanied by a rise in temperature, ultimately reaching around 350 °C as the VOC concentrations ranged from 10% to 30%. At 4% hydrogen, a similar trend was noted, with the maximum temperature exceeding 420 °C (Figure 9).
The fact that the temperature and the CO2 rise abruptly and synchronously without a slow induction time suggests that the reaction temperatures are high enough for the VOCs to oxidize completely. These investigations revealed that hydrogen has the potential to be a very efficient enhancer of the catalytic combustion of VOCs [30,33]. For a deeper comprehension of the function of the bimetallic catalyst, the relationship between active sites and other reaction parameters, and the reaction itself, DFT (Density Functional Theory) studies provide valuable insights into catalysts’ electronic structure and active sites by modeling electron density and interactions. These studies help explain how modifications like alloying or doping impact catalytic activity and selectivity, guiding the optimization of catalyst performance at the atomic level for various applications [34,35,36].

2.3. Electric Heating and Onsite Heating

In fixed-bed reactors, precise temperature control is crucial for catalytic processes, and the choice of heating method, either electric heating via a resistance furnace or onsite hydrogen combustion, significantly impacts efficiency. Electric heating uses an external furnace to elevate the reactor temperature and compensate for heat losses through radiation and conduction. In contrast, hydrogen combustion directly heats the catalyst bed, with most H2 chemical energy efficiently used to elevate the temperature of the catalytically active metal sites. The combustion process also integrates volatile organic compounds (VOCs) into the reaction, enhancing efficiency. Unlike electric heating, hydrogen co-combustion is more energy-efficient, eliminating the need to heat the reactor and the furnace simultaneously. However, accurately measuring the temperature of individual metal sites is difficult, so the catalyst bed temperature is often used as a substitute. Therefore, it is imperative to develop novel heating techniques to improve the efficiency of reactors. Also, to use this method on a larger scale, such as for industrial application where mixtures of VOCs (such as nitrogen- and sulfur-containing compounds) release toxic compounds results in the poisoning of the catalyst. Therefore, a catalyst that can oxidize VOCs efficiently and possesses good sulfur resistance is highly desirable for its environmental application in VOC removal [22,37,38].

3. Experimental Section

3.1. Catalyst Preparation

A (Pt-Co)/Al2O3 (PM) catalyst was prepared using the incipient wetness impregnation method. Initially, 100 g of spherical alumina (2–3 mm, Tianjin Xidian Chemical Technology, Tianjin, China) was impregnated with 100 mL of a Pt(NO3)3·6H2O solution (Tianjin Fengchuan Chemical Reagent Technology Co., Ltd., Tianjin, China) containing 10 g/L of platinum to achieve a 1 wt% Pt loading on the alumina. The impregnated sample was then dried at 120 °C for eight hours, calcined at 500 °C for five hours with a heating rate of 5 °C/min, and reduced in H2 at 500 °C for two hours with a flow rate of 300 mL/min.
Similarly, a 1 wt% cobalt solution (Co(NO3)2·6H2O, >99.9%, Tianjin Fengchuan Chemical Reagent Technology Co., Ltd., Tianjin, China)was supported on alumina following the same procedure. After preparing both catalysts, they were combined into a physical mixture, which is denoted as (Pt-Co)/Al2O3 (PM).

3.2. Catalyst Characterizations

The specific surface areas of the fresh and spent catalysts were measured on a Micromeritics ASAP 2460 (Norcross, GA, USA) by N2 adsorption at −196 °C using the Brunauer–Emmett–Teller (BET) analysis method. The samples’ X-ray diffraction (XRD) patterns were captured using a PANalytical PW 3040/60 X’Pert PRO diffractometer with a Cu K radiation source (λ = 1.5406 Å), operating at 40 kV and 40 mA. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were conducted on a JEOL JEM-2100F at 200 keV. For energy dispersive X-ray spectroscopy (EDS) analysis, an Oxford Instruments ISIS/INCA system with an Oxford Pentafet Ultrathin Window (UTW) Detector was utilized. Specimens were prepared by depositing a suspension of the powdered sample onto a lacey carbon-coated copper grid.

3.3. Reactor Setup and Performance Test

The fixed-bed reactor was a quartz tube, 30 cm long and 10 mm in inner diameter. In the center, 0.5 g of (Pt-Co)/Al2O3 (PM) catalyst, with a volume of 0.78 cm3, was supported by 200 mesh ceramic honeycombs. A K-type thermocouple was inserted into the catalyst bed to measure the temperature. By bubbling the chemical vapors (benzene 99.7%, toluene 99.7%, methanol 99.7%, and formic acid 99.7%, (Fuyu chemicals-Tianjin Fuyu Fine Chemicals Co., Ltd., Tianjin, China) at flow rates of 100, 200, and 300 mL/min, respectively, VOC emissions were replicated. Considering this, the vapor concentrations in a 1000 mL/min total flow were designated as 10%, 20%, and 30% vapor, respectively. The nominal concentrations and calorific values of various compositions of VOC and air mixes are listed in Table 1. As a result, the heat of combustion and the volume of volatile organic compounds (VOCs) were used to estimate the calorific values for the respective combinations. A high-purity hydrogen generator (Beijing Zhonghuipu, SPH-300A, Zhonghuipu Analytical Technology Research Institute) provided the hydrogen. The air and H2 flow rates were regulated by mass flow controllers that were calibrated. The overall flow rate was kept constant at 1000 mL/min, resulting in an hourly space velocity of 120,000 mL/g·h, or 77,000 h−1, for the gas. Using a Hiden Analytical mass spectrometer (HPR-20, R&D, Warrington, UK) the reactants and products were recorded and analyzed by tracking the signals of H2 (m/z = 2), benzene (m/z = 78), toluene (m/z = 91), methanol (m/z = 31), formic acid (m/z = 46), and CO2 (m/z = 44). Utilizing an electric heating furnace set to ramp at a rate of 5 °C/min from room temperature to 750 °C, a temperature-programmed catalytic reaction between VOCs and air over PtCo/Al2O3 (PM) was carried out to determine the light-off temperatures.

4. Conclusions

This work introduces an innovative approach for the catalytic combustion of aromatic volatile and oxygenated compounds (VOCs) by utilizing a (Pt-Co)/Al2O3 (PM), as an alternative to conventional electric heating. The catalyst bed and co-fed VOCs can be precisely heated to fully combust typical compounds such as benzene, toluene, methanol, and formic acid by adjusting the hydrogen concentration below the low explosive limit. The catalyst bed is meticulously elevated to the required temperatures through hydrogen catalytic combustion, facilitating the ignition of volatile organic compounds (VOCs). The results emphasize the exclusive role of hydrogen in VOC destruction, with the degree of combustion contingent on the quantity of hydrogen introduced. Hydrogen-based heating allows pollutants to be pollution-free, achieves rapid temperature elevation, and enhances energy efficiency. A comparative study of energy usage shows that hydrogen co-combustion is the most energy-efficient alternative to conventional electric heating for catalytic VOC oxidation, ensuring a safe and secure process for air pollution control.

Author Contributions

S.M. and L.U. synthesized the catalysts, performed most of the experiments, and collected and analyzed the data. L.C. and J.-C.Z. established the reaction setup and validated the concept. P.R.M. revised the manuscript. W.-Z.L. designed this study and supervised the project. All authors contributed to the general discussion and co-wrote the manuscript. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the “Transformational Technologies for Clean Energy and Demonstration”, Strategic Priority Research Program of the Chinese Academy of Sciences (XDA21040200).

Data Availability Statement

The data presented in this article are either available in the main manuscript or can be provided upon reasonable request from the corresponding author.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

References

  1. Geng, W.; Zhang, J.; Yuan, D.; Sun, R.; Peng, L. Application Study on Three-Bed Regenerative Thermal Oxidizers to Treat Volatile Organic Compounds. IOP Conf. Ser. Earth Environ. Sci. 2018, 170, 042137. [Google Scholar] [CrossRef]
  2. Lin, F.; Zhang, Z.; Li, N.; Yan, B.; He, C.; Hao, Z.; Chen, G. How to achieve complete elimination of Cl-VOCs: A critical review on byproducts formation and inhibition strategies during catalytic oxidation. Chem. Eng. J. 2021, 404, 126534. [Google Scholar] [CrossRef]
  3. Guo, M.; Li, K.; Zhang, H.; Min, X.; Liang, J.; Hu, X.; Guo, W.; Jia, J.; Sun, T. Promotional removal of oxygenated VOC over manganese-based multi oxides from spent lithium-ions manganate batteries: Modification with Fe, Bi and Ce dopants. Sci. Total Environ. 2020, 740, 139951. [Google Scholar] [CrossRef] [PubMed]
  4. Zhang, C.; Chu, W.; Chen, F.; Li, L.; Jiang, R.; Yan, J. Effects of cerium precursors on surface properties of mesoporous CeMnOx catalysts for toluene combustion. J. Rare Earths 2020, 38, 70–75. [Google Scholar] [CrossRef]
  5. Schnelle Jr, K.B.; Brown, C.A. Air Pollution Control Technology Handbook; CRC Press: Boca Raton, FL, USA, 2016. [Google Scholar]
  6. Us, E. Control Technologies for Hazardous Air Pollutants; EPA/625/6-91/014; US Environmental Protection Agency: Washington, DC, USA, 1991. [Google Scholar]
  7. Liu, B.; Ji, J.; Zhang, B.; Huang, W.; Gan, Y.; Leung, D.Y.; Huang, H. Catalytic ozonation of VOCs at low temperature: A comprehensive review. J. Hazard. Mater. 2022, 422, 126847. [Google Scholar] [CrossRef]
  8. Brown, R.W.; Bull, I.D.; Journeaux, T.; Chadwick, D.R.; Jones, D.L. Volatile organic compounds (VOCs) allow sensitive differentiation of biological soil quality. Soil Biol. Biochem. 2021, 156, 108187. [Google Scholar] [CrossRef]
  9. Muir, B.; Sobczyk, M.; Bajda, T. Fundamental features of mesoporous functional materials influencing the efficiency of removal of VOCs from aqueous systems: A review. Sci. Total Environ. 2021, 784, 147121. [Google Scholar] [CrossRef]
  10. Yang, Y.; Si, W.; Peng, Y.; Chen, J.; Wang, Y.; Chen, D.; Tian, Z.; Wang, J.; Li, J. Oxygen vacancy engineering on copper-manganese spinel surface for enhancing toluene catalytic combustion: A comparative study of acid treatment and alkali treatment. Appl. Catal. B Environ. 2024, 340, 123142. [Google Scholar] [CrossRef]
  11. Chen, L.; Liao, Y.; Chen, Y.; Wu, J.; Ma, X. Performance of Ce-modified VW-Ti type catalyst on simultaneous control of NO and typical VOCS. Fuel Process. Technol. 2020, 207, 106483. [Google Scholar] [CrossRef]
  12. Shayegan, Z.; Haghighat, F.; Lee, C.-S. Surface fluorinated Ce-doped TiO2 nanostructure photocatalyst: A trap and remove strategy to enhance the VOC removal from indoor air environment. Chem. Eng. J. 2020, 401, 125932. [Google Scholar] [CrossRef]
  13. Li, S.; Wang, D.; Wu, X.; Chen, Y. Recent advance on VOCs oxidation over layered double hydroxides derived mixed metal oxides. Chin. J. Catal. 2020, 41, 550–560. [Google Scholar] [CrossRef]
  14. Ren, S.; Liang, W.; Fang, H.; Zhu, Y. Performance and poisoning analysis of organic sulfur resistance of Pd-Ce catalyst in catalytic oxidation of VOCs. J. Environ. Chem. Eng. 2021, 9, 106640. [Google Scholar] [CrossRef]
  15. Zhang, S.; Pu, W.; Chen, A.; Xu, Y.; Wang, Y.; Yang, C.; Gong, J. Oxygen vacancies enhanced photocatalytic activity towards VOCs oxidation over Pt deposited Bi2WO6 under visible light. J. Hazard. Mater. 2020, 384, 121478. [Google Scholar] [CrossRef]
  16. Liu, G.; Tian, Y.; Zhang, B.; Wang, L.; Zhang, X. Catalytic combustion of VOC on sandwich-structured Pt@ ZSM-5 nanosheets prepared by controllable intercalation. J. Hazard. Mater. 2019, 367, 568–576. [Google Scholar] [CrossRef]
  17. Shi, Y.; Wang, J.; Zhou, R. Pt-support interaction and nanoparticle size effect in Pt/CeO2–TiO2 catalysts for low temperature VOCs removal. Chemosphere 2021, 265, 129127. [Google Scholar] [CrossRef] [PubMed]
  18. He, Z.; He, Z.; Wang, D.; Bo, Q.; Fan, T.; Jiang, Y. Mo-modified Pd/Al2O3 catalysts for benzene catalytic combustion. J. Environ. Sci. 2014, 26, 1481–1487. [Google Scholar] [CrossRef]
  19. Tahsini, N.; Yang, A.-C.; Streibel, V.; Werghi, B.; Goodman, E.D.; Aitbekova, A.; Bare, S.R.; Li, Y.; Abild-Pedersen, F.; Cargnello, M. Colloidal Platinum–Copper Nanocrystal Alloy Catalysts Surpass Platinum in Low-Temperature Propene Combustion. J. Am. Chem. Soc. 2022, 144, 1612–1621. [Google Scholar] [CrossRef]
  20. Dietrich, P.J.; Akatay, M.C.; Sollberger, F.G.; Stach, E.A.; Miller, J.T.; Delgass, W.N.; Ribeiro, F.H. Effect of Co Loading on the Activity and Selectivity of PtCo Aqueous Phase Reforming Catalysts. ACS Catal. 2014, 4, 480–491. [Google Scholar] [CrossRef]
  21. Wu, D.; Jia, R.; Wen, M.; Zhong, S.; Wu, Q.; Fu, Y.; Yu, S. Ultrastable PtCo/Co3O4-SiO2 Nanocomposite with Active Lattice Oxygen for Superior Catalytic Activity toward CO Oxidation. Inorg. Chem. 2020, 59, 1218–1226. [Google Scholar] [CrossRef]
  22. Gao, L.; Liu, J.; Zhong, X.; Zhang, Y.; Chen, J.; Shakeri, M.; Zhang, X.; Zhang, B. Structural Regulation of PtCo/Y Zeolite Catalysts for the Selective Hydrogenation of 3-Nitrostyrene to 3-Vinylaniline. ACS Appl. Nano Mater. 2023, 6, 5685–5691. [Google Scholar] [CrossRef]
  23. Zhu, A.; Zhou, Y.; Wang, Y.; Zhu, Q.; Liu, H.; Zhang, Z.; Lu, H. Catalytic combustion of VOCs on Pt/CuMnCe and Pt/CeY honeycomb monolithic catalysts. J. Rare Earths 2018, 36, 1272–1277. [Google Scholar] [CrossRef]
  24. Kozhukhova, A.E.; du Preez, S.P.; Bessarabov, D.G. Catalytic hydrogen combustion for domestic and safety applications: A critical review of catalyst materials and technologies. Energies 2021, 14, 4897. [Google Scholar] [CrossRef]
  25. Zhong, B.-J.; Yang, Q.-T.; Yang, F. Hydrogen-assisted catalytic ignition characteristics of different fuels. Combust. Flame 2010, 157, 2005–2007. [Google Scholar] [CrossRef]
  26. Deutschmann, O.; Maier, L.; Riedel, U.; Stroemman, A.; Dibble, R. Hydrogen assisted catalytic combustion of methane on platinum. Catal. Today 2000, 59, 141–150. [Google Scholar] [CrossRef]
  27. Yuan, L.-J.; Zhao, Z.-C.; Wang, W.-Q.; Wang, Y.-F.; Liu, Y.-J. Review of Catalysts, Substrates, and Fabrication Methods in Catalytic Hydrogen Combustion with Further Challenges and Applications. Energy Fuels 2024, 38, 4881–4903. [Google Scholar] [CrossRef]
  28. Hansen, T.W.; DeLaRiva, A.T.; Challa, S.R.; Datye, A.K. Sintering of catalytic nanoparticles: Particle migration or Ostwald ripening? Acc. Chem. Res. 2013, 46, 1720–1730. [Google Scholar] [CrossRef]
  29. Ullah, L.; Munsif, S.; Cao, L.; Zhang, J.-C.; Li, W.-Z. Facile Abatement of Oxygenated Volatile Organic Compounds via Hydrogen Co-Combustion over Pd/Al2O3 Catalyst as Onsite Heating Source. Catalysts 2024, 14, 372. [Google Scholar] [CrossRef]
  30. Ullah, L.; Munsif, S.; Cao, L.; Murthy, P.R.; Zhang, J.-C.; Li, W.-Z. Hydrogen Co-Combustion of Aromatic Volatile Organic Compounds over Pd/Al2O3 Catalyst. Catalysts 2024, 14, 563. [Google Scholar] [CrossRef]
  31. Ladacki, M.; Houser, T.J.; Roberts, R.W. The catalyzed low-temperature hydrogen-oxygen reaction. J. Catal. 1965, 4, 239–247. [Google Scholar] [CrossRef]
  32. Kim, S.C.; Shim, W.G. Properties and performance of Pd based catalysts for catalytic oxidation of volatile organic compounds. Appl. Catal. B Environ. 2009, 92, 429–436. [Google Scholar] [CrossRef]
  33. Kim, J.; Yu, J.; Lee, S.; Tahmasebi, A.; Jeon, C.-H.; Lucas, J. Advances in catalytic hydrogen combustion research: Catalysts, mechanism, kinetics, and reactor designs. Int. J. Hydrogen Energy 2021, 46, 40073–40104. [Google Scholar] [CrossRef]
  34. Guo, Y.; Sun, Y.; Yang, D.P.; Dai, J.; Liu, Z.; Chen, Y.; Huang, J.; Li, Q. Biogenic Pt/CaCO3 Nanocomposite as a Robust Catalyst toward Benzene Oxidation. ACS Appl. Mater. Interfaces 2020, 12, 2469–2480. [Google Scholar] [CrossRef] [PubMed]
  35. Hou, Z.; Lu, Y.; Liu, Y.; Liu, N.; Hu, J.; Wei, L.; Li, Z.; Tian, X.; Gao, R.; Yu, X.; et al. A General Dual-Metal Nanocrystal Dissociation Strategy to Generate Robust High-Temperature-Stable Alumina-Supported Single-Atom Catalysts. J. Am. Chem. Soc. 2023, 145, 15869–15878. [Google Scholar] [CrossRef] [PubMed]
  36. Xia, L.; Jian, Y.; Liu, Q.; Liu, Y.; Wang, J.; Chai, S.; Jing, M.; Albilali, R.; He, C. Boosted Light Alkane Deep Oxidation via Metal Bond Length Modulation-Induced C–C Bond Preferential Activation. Environ. Sci. Technol. 2024, 58, 3472–3482. [Google Scholar] [CrossRef] [PubMed]
  37. Hao, X.; Deng, J.; Liu, Y.; Jing, L.; Wang, J.; Wang, Z.; Dai, H. Mesoporous NaxMnOy-Supported Platinum–Cobalt Bimetallic Single-Atom Catalysts with Good Sulfur Dioxide Tolerance in Propane Oxidation. ACS Sustain. Chem. Eng. 2022, 10, 8326–8341. [Google Scholar] [CrossRef]
  38. Wang, X.; Yu, H.; Hua, D.; Zhou, S. Enhanced Catalytic Hydrogenation Activity and Selectivity of Pt-MxOy/Al2O3 (M = Ni, Fe, Co) Heteroaggregate Catalysts by in Situ Transformation of PtM Alloy Nanoparticles. J. Phys. Chem. C 2013, 117, 7294–7302. [Google Scholar] [CrossRef]
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Figure 1. XRD patterns for fresh and spent (Pt-Co)/Al2O3 (PM) catalysts.
Figure 1. XRD patterns for fresh and spent (Pt-Co)/Al2O3 (PM) catalysts.
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Figure 2. (a–d). STEM and EDX images of fresh and spent (Pt-Co)/Al2O3 (PM) catalysts.
Figure 2. (a–d). STEM and EDX images of fresh and spent (Pt-Co)/Al2O3 (PM) catalysts.
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Catalysts 14 00729 g003
Figure 3. Temperatures of the catalyst bed for 2%, 3%, and 4% of H2 in the air with a total flow of 1000 mL/min over 0.5 g of (Pt-Co)/Al2O3 (PM) catalyst (GHSV: 120,000 mL/(h·g)).
Figure 3. Temperatures of the catalyst bed for 2%, 3%, and 4% of H2 in the air with a total flow of 1000 mL/min over 0.5 g of (Pt-Co)/Al2O3 (PM) catalyst (GHSV: 120,000 mL/(h·g)).
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Catalysts 14 00729 g004
Figure 4. Light−off curves illustrated by CO2 formation and catalyst bed temperature rising profiles during the temperature-programmed reaction of benzene, toluene, methanol, and formic acid over the fresh (Pt-Co)/Al2O3 (PM) catalyst using an electric heating furnace. The VOC concentrations were controlled at 10% vapor, and the temperature from 0 to 725 °C with a ramping rate was 5 °C/min.
Figure 4. Light−off curves illustrated by CO2 formation and catalyst bed temperature rising profiles during the temperature-programmed reaction of benzene, toluene, methanol, and formic acid over the fresh (Pt-Co)/Al2O3 (PM) catalyst using an electric heating furnace. The VOC concentrations were controlled at 10% vapor, and the temperature from 0 to 725 °C with a ramping rate was 5 °C/min.
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Catalysts 14 00729 g005
Figure 5. Light−off curves illustrated by CO2 formation and catalyst bed temperature rising profiles during the temperature-programmed reaction of benzene, toluene, methanol and formic acid over spent (Pt-Co)/Al2O3 (PM) catalyst using electric heating furnace, respectively. The VOC concentrations were controlled at 10% vapor and the temperature from 0 to 725 °C with ramping rate was 5 °C/min.
Figure 5. Light−off curves illustrated by CO2 formation and catalyst bed temperature rising profiles during the temperature-programmed reaction of benzene, toluene, methanol and formic acid over spent (Pt-Co)/Al2O3 (PM) catalyst using electric heating furnace, respectively. The VOC concentrations were controlled at 10% vapor and the temperature from 0 to 725 °C with ramping rate was 5 °C/min.
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Catalysts 14 00729 g006
Figure 6. (a–c). CO2 formation curves and the corresponding catalyst bed temperature profiles of benzene with the co-combustion of 2% (a), 3% (b), and 4% (c) of H2 with a total flow of 1000 mL/min over 0.5 g of (Pt-Co)/Al2O3 (PM) catalyst (GHSV: 120,000 mL/(h·g)), at a 10%, 20%, and 30% vapor concentration of VOCs, respectively.
Figure 6. (a–c). CO2 formation curves and the corresponding catalyst bed temperature profiles of benzene with the co-combustion of 2% (a), 3% (b), and 4% (c) of H2 with a total flow of 1000 mL/min over 0.5 g of (Pt-Co)/Al2O3 (PM) catalyst (GHSV: 120,000 mL/(h·g)), at a 10%, 20%, and 30% vapor concentration of VOCs, respectively.
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Catalysts 14 00729 g007
Figure 7. (a–c). CO2 formation curves and the corresponding catalyst bed temperature profiles of toluene with the co-combustion of 2% (a), 3% (b), and 4% (c) of H2 with a total flow of 1000 mL/min over 0.5 g of (Pt-Co)/Al2O3 (PM) catalyst (GHSV: 120,000 mL/(h·g)), at a 10%, 20%, and 30% vapor concentration of VOCs, respectively.
Figure 7. (a–c). CO2 formation curves and the corresponding catalyst bed temperature profiles of toluene with the co-combustion of 2% (a), 3% (b), and 4% (c) of H2 with a total flow of 1000 mL/min over 0.5 g of (Pt-Co)/Al2O3 (PM) catalyst (GHSV: 120,000 mL/(h·g)), at a 10%, 20%, and 30% vapor concentration of VOCs, respectively.
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Figure 8. (a–c). CO2 formation curves and the corresponding catalyst bed temperature profiles of methanol with the co-combustion of 2% (a), 3% (b), and 4% (c) of H2 with a total flow of 1000 mL/min over 0.5 g of (Pt-Co)/A2O3 (PM) catalyst (GHSV: 120,000 mL/(h·g)), at a 10%, 20%, and 30% vapor concentration of VOCs, respectively.
Figure 8. (a–c). CO2 formation curves and the corresponding catalyst bed temperature profiles of methanol with the co-combustion of 2% (a), 3% (b), and 4% (c) of H2 with a total flow of 1000 mL/min over 0.5 g of (Pt-Co)/A2O3 (PM) catalyst (GHSV: 120,000 mL/(h·g)), at a 10%, 20%, and 30% vapor concentration of VOCs, respectively.
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Catalysts 14 00729 g009
Figure 9. (a–c). CO2 formation curves and the corresponding catalyst bed temperature profiles of formic acid with the co-combustion of 2% (a), 3% (b), and 4% (c) of H2 with a total flow of 1000 mL/min over 0.5 g of (Pt-Co)/Al2O3 (PM) catalyst (GHSV: 120,000 mL/(h·g)), at a 10%, 20%, and 30% vapor concentration of VOCs, respectively.
Figure 9. (a–c). CO2 formation curves and the corresponding catalyst bed temperature profiles of formic acid with the co-combustion of 2% (a), 3% (b), and 4% (c) of H2 with a total flow of 1000 mL/min over 0.5 g of (Pt-Co)/Al2O3 (PM) catalyst (GHSV: 120,000 mL/(h·g)), at a 10%, 20%, and 30% vapor concentration of VOCs, respectively.
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Table 1. Vapor pressures and heat of combustion for various VOCs, and the nominal concentrations and calorific values of mixtures of VOCs and air in different compositions.
Table 1. Vapor pressures and heat of combustion for various VOCs, and the nominal concentrations and calorific values of mixtures of VOCs and air in different compositions.
Chemical
Hydrogen		Vapor
Pressure
(20 °C, kPa)
286		Heat of
Combustion
(25 °C, kJ/mol)		Nominal
Concentration (%)		Calorific Value
(kJ/m3)
10% Vapor20% Vapor30% Vapor10%
Vapor		20%
Vapor		30%
Vapor
Benzene1032630.991.982.991435.222844335
Toluene939100.290.580.57504 1012 1517
Methanol137251.32.63.9420.8 841.5 1262.3
Formic Acid4.6254.60.50.91.4 56.8102.3159.1
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Munsif, S.; Ullah, L.; Cao, L.; Murthy, P.R.; Zhang, J.-C.; Li, W.-Z. A Highly Efficient Catalytic Co-Combustion of Aromatic and Oxygenated Volatile Organic Compounds (VOCs) via H2-Driven Onsite Heating. Catalysts 2024, 14, 729. https://doi.org/10.3390/catal14100729

AMA Style

Munsif S, Ullah L, Cao L, Murthy PR, Zhang J-C, Li W-Z. A Highly Efficient Catalytic Co-Combustion of Aromatic and Oxygenated Volatile Organic Compounds (VOCs) via H2-Driven Onsite Heating. Catalysts. 2024; 14(10):729. https://doi.org/10.3390/catal14100729

Chicago/Turabian Style

Munsif, Sehrish, Lutf Ullah, Long Cao, Palle Ramana Murthy, Jing-Cai Zhang, and Wei-Zhen Li. 2024. "A Highly Efficient Catalytic Co-Combustion of Aromatic and Oxygenated Volatile Organic Compounds (VOCs) via H2-Driven Onsite Heating" Catalysts 14, no. 10: 729. https://doi.org/10.3390/catal14100729

APA Style

Munsif, S., Ullah, L., Cao, L., Murthy, P. R., Zhang, J.-C., & Li, W.-Z. (2024). A Highly Efficient Catalytic Co-Combustion of Aromatic and Oxygenated Volatile Organic Compounds (VOCs) via H2-Driven Onsite Heating. Catalysts, 14(10), 729. https://doi.org/10.3390/catal14100729

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