Adsorption separation of vinyl chloride and acetylene on activated carbon modified by metal ions
Introduction
In the last decade, with the sustained development of construction industry, the demand of polyvinyl chloride (PVC) increased rapidly which accounted for about 20% of plastic material usage [1]. Vinyl chloride (C2H3Cl), as the monomer during the polymerization process, was mainly obtained by hydrochlorination of acetylene (C2H2), which named by calcium carbide route [2], [3]. However, the tail gas of calcium carbide route contained abundant C2H3Cl and C2H2, if it directly discharged into the atmosphere without any treatment, not only it polluted the environment, but also caused an enormous waste of resources [4], [5].
At present, adsorption separation technique was widely used to treat the PVC tail gas [6], [7]. As the core of adsorption separation, adsorbents with high selectivity of C2H3Cl to C2H2 was still needed, which made C2H3Cl return to the polymerization process, C2H2 return to the process of hydrochlorination [8], [9]. The reported adsorbents included silica gel, activated alumina, zeolite-based materials and carbon-based materials [10]. As porous materials with high specific surface areas and large pore volume, activated carbon (AC) was one of the most important adsorbents, which has been studied for the tail gas treatment [11].
In this paper, six metal ions, Al3+, Mg2+, Fe3+, Zn2+, Cu2+ and Ag+ were separately loaded on the AC to obtain the modified activated carbons. The effect of metal ions on the adsorption separation of C2H3Cl and C2H2 were investigated, and the influence of the hardness of metal ions on the separation factor of C2H3Cl to C2H2 was discussed.
Section snippets
Materials
The adsorbate (10% vinyl chloride, 10% C2H2 and balance with helium) was purchased from Southwest Research Institute of Chemical Industry. The composition simulated the tail gas of the PVC factory.
The AC (40–50 mesh) based on coconut shell, which supplied by Ningxia Activated Carbon Company, China. The other reagents, Mg(NO3)2, Al(NO3)3, Fe(NO3)3, Cu(NO3)2, Zn(NO3)2 and AgNO3, were all analytical.
Preparation of adsorbents
Al(III)/AC, Mg(II)/AC, Fe(III)/AC, Zn(II)/AC, Cu(II)/AC and Ag(I)/AC were prepared by impregnating
Breakthrough curves of C2H2 and C2H3Cl
The breakthrough curves of C2H2 and C2H3Cl on modified ACs by different metal ions have similar shape with the original AC, therefore the original AC was chosen to illustrate the adsorption separation process, as shown in Fig. 2. In order to describe the adsorption process in detailed, the breakthrough curves of C2H2 and C2H3Cl were discussed, which marked as the curve “a-b-c-d-e-f” and “a-g-h-f” separately. C/C0 = 0.05(b, g), was generally defined as “breakthrough point”, which meant C2H2 or C2H3
Conclusions
The adsorption separation of C2H3Cl and C2H2 on modified AC by metal ions with different hardness was investigated. The adsorption capacity of C2H2 and C2H3Cl decreases with the rising of metal ion absolute hardness, Compared with the original activated carbon, Al3+, Mg2+ and Fe3+ weaken the interaction with C2H2 and C2H3Cl, while Zn2+, Cu2+and Ag+ could enhance the interaction with C2H2 and C2H3Cl. The influence of the hardness of metal ions on the adsorption capacity of C2H2 is more
Acknowledgment
The authors are very grateful to acknowledge the National High Technology Research and Development Program of China (2008AA062601) for financial support.
References (25)
- et al.
Journal of Loss Prevention in the Process Industries
(2002) - et al.
Carbon
(1996) - et al.
Applied Surface Science
(2004) - et al.
Journal of Colloid and Interface Science
(1974) Inorganica Chimica Acta
(1995)- et al.
Catalysis Today
(1999) - et al.
Chemical Physics Letters
(2004) - et al.
Chlorine: Principles and Industrial Practice
(2000) - et al.
Petroleum Science and Technology
(2010) - et al.
Green Chemistry
(2011)
The Clean Air Act of 1990: A Primer on Consensus Building
Vinyl Chloride, Environmental Health Criteria
Cited by (12)
Synthesis of hierarchical porous carbon with high surface area by chemical activation of (NH<inf>4</inf>)<inf>2</inf>C<inf>2</inf>O<inf>4</inf> modified hydrochar for chlorobenzene adsorption
2023, Journal of Environmental Sciences (China)Citation Excerpt :However, it is challenging to develop carbonaceous materials with satisfactory performance of VOCs adsorption. The adsorption performance of porous carbon material depends upon its properties, like surface area, pore size, and surface functional group (Jiang et al., 2014; Silva et al., 2021). These physical and chemical properties largely rely on the raw materials and preparation techniques.
Influence of hydrocarbons on hydrogen chloride removal from refinery off-gas by zeolite NaY derived from rice husks
2020, Science of the Total EnvironmentCitation Excerpt :The high adsorption capacities obtained in the presence of alkenes is attributed to the formation of vinyl chloride monomers (VCM) from the reaction between HCl and alkenes (Scharfe et al., 2016). Based on the hard and soft acid and base (HSAB) principle, VCM is favorably adsorbed by zeolite NaY due to the strong acidic nature of zeolite NaY and VCM being classified as a borderline base with an electronegativity of 3.0 eV (Jiang et al., 2014). On the other hand, zeolite NaY soaked in aromatic oil had lower adsorption capacities at breakthrough and saturation compared to fresh zeolites.
Correlation verification of process factors and harmful gas adsorption properties for optimization of physical activation parameters of PAN-based carbon fibers
2019, Journal of Industrial and Engineering ChemistryCitation Excerpt :Porous materials, including Al2O3, MOF (metal organic framework), zeolite, and activated carbon, are now being widely used as materials for adsorbents [1–7]. Among them, activated carbon is the most widely used because it provides high specific surface area and easy control of its internal pore structures [8,9]. Under the standards of the International Union of Pure and Applied Chemistry (IUPAC), pores are divided according to size into micropores with a diameter of 2 nm less, mesopores with diameters ranging from 2 to 50 nm, and macropores with a diameter of 50 nm or above [10].
Preparation of CuFe nanocomposites loaded diatomite and their excellent performance in simultaneous adsorption/oxidation of hydrogen sulfide and phosphine at low temperature
2017, Separation and Purification TechnologyCitation Excerpt :Several studies agree that activated carbon (AC) or modified activated carbon (MAC) have a good removal capacity of hydrogen sulfide and/or phosphine. However, literature [11] has shown that the of activated carbon could adsorb acetylene at the initial reaction phase, so it has the adsorption capacity for a part of the acetylene gas, thus AC or MAC cannot be used to separate the PH3/H2S and acetylene gas. On the contrary, activated alumina (γ-Al2O3) and mesoporous silica hardly adsorb acetylene gas [12].
CuCl<inf>2</inf> promoted low-gold-content Au/C catalyst for acetylene hydrochlorination prepared by ultrasonic-assisted impregnation
2016, Journal of Industrial and Engineering ChemistryCitation Excerpt :Polyvinylchloride (PVC) is one of the five world's top engineering plastics and widely used in the chemical industry. Vinyl chloride monomer (VCM) is the main monomer of PVC, and can be manufactured by processes based on ethylene, acetylene and ethane [1,2]. Although VCM synthesized by ethene largely superseded in many countries, the manufacture of vinyl chloride using coal-rich acetylene hydrochlorination can be expected to remain an important production route in coal enriched western region in China [3].
Bimetallic Au-Sn/AC catalysts for acetylene hydrochlorination
2016, Journal of Industrial and Engineering ChemistryCitation Excerpt :Polyvinyl chloride (PVC) is one of the five widely used engineering plastics. In recent years, with the rapid development of the global world, the demand of PVC increases dramatically [1]. It was reported that the PVC world market reached a total volume of 34 million tons in 2008, while PVC demand was expected to be more than 40 million tons in 2016 [2,3].