Production Of Larger Size SDB Hydrophobic Catalyst Carrier And Its Mass Transfer Resistance In Exchange Column

Liquid phase catalytic exchange(LPCE) is an efficient approach for separating tritium from heavy water and removing tritium from waste water, and the hydrophobic catalysts play a key role in LPCE. Pt/SDB hydrophobic catalysts with high hydrophobic have faced the problems of poor stability, large bed resistance and flooding. To maximize catalyst performances, it is necessary to improve the catalyst efficiency,loading stability and mass transfer resistance of hydrophobic catalysts from the shape,size, and preparation conditions. Usually, the active component of hydrophobic catalyst is Pt, the amount of which is too small(0.1~1.0 wt%) to impacted the mass transfer resistance performances of hydrophobic catalysts. Therefore, SDB was used to instead of Pt/SDB to study the mass transfer resistance in this research.Using styrene(St) as a monomer and divinylbenzene(DVB) as cross-linking agent,SDB with particles sizes of 1.3mm, 2.4mm, and 3.3mm were synthesized by suspension polymerization according to turning the stirring speed. The structures and properties of products were characterized by fourier transform infrared spectroscopy(FT-IR), water static contact angle(CA), thermogravimetric analysis(TG), scanning electronic microscopy(SEM). Meanwhile, the effect of packing mode and volume ratio of SDB carrier to stainless steel ? packing on the pressure drop of column were investigated.Similarly, the effect of gas and liquid flow rate, as well as temperature on the pressure drop of column and liquid holdup were studied. Performance tests demonstrated when the molar ratio of DVB to St was 1:1, SDB had high thermal stability(420.78?) and hydrophobic(130.91°), and the surface smoothness decreases with the increase of particle size. The pressure drop of layered packing was higher than mixed packing.Thus, the pressure drop decreased with the increasing of the packing volume ratio until4:1. For the pressure drop of different layered packing, the sort from largest to smallestwas four, three, one, and two. Moreover, with the increasing of gas and liquid flow rate,as well as temperature, the pressure drop of column increased. Interestingly, the liquid holdup decreased with the gas flow rate increasing, while increased with the liquid flow rate increasing. It was worth noting that the phenomenon above was significant when the partical size of SDB carriers decreased.Using starch, polyvinylpyrrolidone(PVP), carboxymethyl cellulose(CMC),polyvinyl alcohol(PVA) as binder, cylindrical SDB was prepared by pressure. The structures and properties of products were characterized by FT-IR, CA, TG, and electronic universal test. The mass transfer resistance experiments were conducted employing a mixed packing mode with volume ratio of 1:4. Performance tests demonstrated the cylindrical SDB using PVA as a binder with amount of 0.401% had big contact angle of 144.83 o, high compressive strength of above 3000 KPa, good thermal stability and satisfied pore structure. To reduce the impact of PVA on the carrier hydrophobic, 5% polytetrafluoroethylene(PTFE) was added giving the best hydrophobic. The pressure drop of column increased with the increasing of the gas and liquid flow rate, and the temperature. Compared with spherical SDB, the pressure drop and liquid holdup of cylindrical SDB were obviously decreased.Pt/SDB hydrophobic catalyst was prepared through an impregnating method with spherical SDB used as a carrier. The structures of Pt/SDB, as well as the relationship between residual double bonds and catalytic activity of Pt/SDB were characterized by chemical titration, electronic universal test, X-ray diffraction(XRD), TG, X-ray photoelectron spectroscopy(XPS), LPCE. Results indicate that the contents of residual double bonds were positively related to the dosage of DVB. And with the increasing of residual double bonds contents, the compressive strength firstly increases and then decreases, which reached to the maximum(31.087 N) at the molar ratio of DVB to St was 1:1. The loading amounts of Pt increase correspondingly with the contents of residual double bonds when the molar ratio of DVB to St were 1:1, 4:5, and 3:5. The column efficiencies of Pt/SDB with a highest content of residual double bond were thebest and all above 90% under all the experimental conditions. It was probably due to the electronic delocalization effect formed between the d orbital of Pt and ? conjugated ligand of benzene ring and residual double bond, which was from the electrons transferred from Pt to the SDB. The stabilities and catalytic activities of Pt/SDB enhanced with the contents of residual double bonds increased.Different sizes of spherical and cylindrical SDB were successfully prepared and used to study the mass transfer resistance. Pt/SDB hydrophobic catalyst has high catalytic activity and stability. Therefore, the work will improve the engineering application of Pt/SDB.