Dichloropropanol Research Articles

Stitch and copolymerization of thin-film composite membranes to enhance hydrophilicity and organics resistance for the separation of glycerol-based wastewater

Many industries produce large amounts of glycerol-based wastewater, which always contains hazardous organic chlorides. Compared with complicated biological treatments or physical adsorption, membrane separation decreases the cost and saves energy. Strong swelling of traditional thin-film composite (TFC) membranes influence the performance in the separation of organic molecules. Here we prepared TFC membranes with an acrylamide-grafted PAN support layer to copolymerize with m-phenylenediamine (MPD) and trimesoyl chloride (TMC). The link of separative layer and support layer was created like a zipper stitching to enhance the stability and resistance for the removal of organic molecules. An aquatic grass-like layer of acrylamide enlarges the surface area and hydrophilicity with superior separation performances (15.8 LMH bar−1 flux, 72.0% rejection of dichloropropanol (DCP) and 64.6% rejection of glycerol (Gl)). The trade-off upper bound was improved to a high level. We also established the simulations of evaporation using Aspen Plus and mathematical models of reverse osmosis to calculate the energy consumption corresponding to the recycle of glycerol-based wastewater. The experimental and theoretical results illustrate the advantages of acrylamide-grafted TFC membranes in the ap-plications to concentrate organic solutes and treat wastewater.

Understanding the pathways of improved chlorohydrination of allyl chloride with HCl and H2O2 catalyzed by titanium-incorporated zeolites

Chlorine based olefin chlorohydrination reaction is one of the most hazard and polluted processes for manufacturing epoxy compounds. To solve these drawbacks, we have exploited a totally novel allyl chloride chlorohydrination route, using HCl and H2O2 as raw materials, catalyzed by hollow titanium silicate (HTS) zeolite. Under optimal parameters, almost 100% allyl chloride conversion and over 98.0% dichloropropanol (DCP) selectivity have been achieved, and HTS zeolite displays pretty high stability in strong acidic solution for over 25days. UV-Raman spectroscopy directly reveals the formation of Cl2 and its derivates, but this chlorohydrination is also competitively dominated by an epoxidation-ring opening mechanism, especially in high catalyst dosage. That is because allyl chloride is much easier to be epoxidized to epichlorohydrin (ECH) under HTS catalyst, rather than reacts with Cl-containing species generated via the HCl oxidation with H2O2. Meanwhile, ECH is highly active to react with HCl to form 1,3-DCP catalyzed by H+ ions, thus the epoxidation process can be significantly promoted by ring-opening reaction, due to the pushing of chemical balance. Importantly, this study provides a novel viewpoint on developing green chemical processes, on the basis of their fundamental reaction mechanisms.

The simulation of epichlorohydrin production process by using naoh instead of ca(oh)2 based on the reaction kinetics

The epichlorohydrin (ECH) were prepared by the method of dichloropropanol (DCH) saponified with Ca(OH)2, while using Ca(OH)2 as reactant, it could bring out some disadvantages, such as equipment jam and environment pollution. In this research, NaOH had been used as the alkali instead of Ca(OH)2 to react with the DCH to resolve the above questions. Firstly, the reaction kinetics of DCH saponification and ECH hydrolysis under NaOH circumstances were obtained by the experiments. Secondly, based on the obtained reaction kinetics and the appropriate thermodynamics, the mathematic models of DCH saponification processes under Ca(OH)2 and NaOH circumstances were built respectively. Thirdly, with comparison and analysis of the two cases, the operation parameters of DCH saponified in NaOH case had been optimized and gained the appropriate operation parameters. The results showed that, in the NaOH case the reaction speed of DCH saponification and ECH hydrolysis were more quickly compared to Ca(OH)2 case. So, if taking the NaOH instead of Ca(OH)2 as alkali, the residence time of reactants must been considered in order to reduce the ECH hydrolysis. Compared to Ca(OH)2 case, the optimum operating condition in NaOH case were modified. The results showed that in the feasible conditions, using NaOH instead of Ca(OH)2 as alkali in the saponification process could be achieved. And more, the CODs (Chemical Oxygen Demands) in wastewater was not yet increase, while the yield of ECH increased from 96.21 % (in case of Ca(OH)2) to 98.44 % (in case of NaOH).

Evaluation of an improved epichlorohydrin synthesis from dichloropropanol using a microchemical system

Synthesizing epichlorohydrin (ECH) from dichloropropanol (DCP) is a complicated reaction due to the partial decomposition of ECH under harsh conditions. A microchemical system can provide a feasible platform for improving this process by conducting a separation once full conversion has been achieved. In this work, referring to a common DCP feed used in industry, the reaction performance of mixed DCP isomers with NaOH in the microchemical system on various time scales was investigated. The operating window for achieving high conversion and selectivity was on a time scale of seconds, while the side reactions normally occurred on a time scale of minutes. Plenty of Cl− ions together with a high temperature were proved to be critical factors for ECH hydrolysis. A kinetic study of alkaline mediated ECH hydrolysis was performed and the requirements for an improved ECH synthesis were proposed by combining quantitative analysis using a simplified reaction model with experimental results on the time scale of minutes. Compared with the conventional distillation process, this new strategy for ECH synthesis exploited microchemical system and decoupled the reaction and separation with potentials of higher productivity and better reliability in scaling up.

Corrosion characteristics of electroless Ni–P coating in dichloropropanol (DCP) solution

Corrosion of reactors or heat exchangers is a major problem in industrial applications. During the industrial production of epichlorohydrin (ECH) from dichloropropanol (DCP), there are many corrosive byproducts which can severely attack heat exchangers. It is therefore important to select suitable structural materials, which are compatible with the field environment of each particular process, to ensure the long term integrity of the reactor components. The aim of the present study is to evaluate the corrosion behaviour of the electroless Ni–P coating in the DCP solution and to gain an improved understanding of the corrosion mechanism. Type 304 stainless steel (SS) was used in the present study. A parametric study was carried out to investigate the influences of the electroless Ni–P coating thickness, immersion temperature and chloride ion concentration, on the corrosion rate and corrosion morphology of the selected materials. The corrosion rate of type 304 SS was always higher than that of the electroless Ni–P coating in DCP solution. The corrosion rate of the electroless Ni–P coating decreased with its thickness firstly and then increased. Also, the electroless Ni–P coating showed better corrosion resistance than type 304 SS in DCP solution containing chloride.

Modified Kinetic Model for Dichloropropanol Synthesis from Glycerin and Anhydrous HCl at High Pressure

A modified kinetic model for the synthesis of dichloropropanol (DCP) from glycerin and anhydrous HCl has been proposed for high-pressure reactions with a fixed weight ratio of glycerin to acetic acid by considering the volume change arising from the generation of water during the reaction. The yield of DCP was found to be maximized at 130°C and 6 bar. The modified kinetic parameters and high-pressure reaction model were evaluated by high-accuracy fitting to experimental data. The results allowed the creation of a kinetic model suitable for application to DCP synthesis from glycerin and anhydrous HCl at high pressures.

10.2478/s11814-009-0245-0

Methods for regenerating H3PW12O40 catalyst in the solvent-free direct preparation of dichloropropanol (DCP) from glycerol and hydrochloric acid gas were investigated. Regenerated H3PW12O40 catalyst was then applied to the solvent-free direct preparation of DCP. In the solvent-free direct preparation of DCP, selectivity for DCP over H3PW12O40 catalyst regenerated by method I (recovery of solid H3PW12O40 catalyst by evaporating homogeneous liquidphase product solution) significantly decreased with increasing recycling run, while that over H3PW12O40 catalyst regenerated by method II (regeneration of H3PW12O40 catalyst by oxidative calcination of solid product recovered by method I) was slightly decreased with no significant catalyst deactivation with respect to recycling run. On the other hand, selectivity for DCP over H3PW12O40 catalyst regenerated by method III (regeneration of H3PW12O40 catalyst by recrystallization and subsequent oxidative calcination of solid product recovered by method II) was the same as that over fresh catalyst without any catalyst deactivation with respect to recycling run. Thus, method III was found to be the most efficient method for the regeneration of H3PW12O40 catalyst.

Direct preparation of dichloropropanol from glycerol and hydrochloric acid gas using heteropolyacid (HPA) catalyst by heterogeneous gas phase reaction

Direct preparation of dichloropropanol (DCP) from glycerol and hydrochloric acid gas was carried out in a heterogeneous gas phase reactor using H 3PMo 12− X W X O 40 ( X = 0, 3, 6, 9, and 12), H 4SiW 12O 40, and H 4SiMo 12O 40 heteropolyacid (HPA) catalysts. Acid property of the HPA catalyst was determined by NH 3-TPD measurement in order to correlate the catalytic activity with the acid property of the catalyst. Acid strength of the HPA catalyst played a key role in determining the catalytic performance in the reaction. Yield for DCP increased with increasing acid strength of the catalyst. Among the catalysts tested, H 3PW 12O 40 with the highest acid strength showed the highest yield for DCP.

Kinetic model of glycerol chlorination with hydrochloric acid

A new reaction model for dichloropropanol (DCP) synthesis from glycerol chlorination is proposed based on the models reported by Tesser et al. (2007) and Luo et al. (2009). Two reaction steps, glycerol to glycerol-1-acetate and α-MCP to 3-chloropropandiol-1-acetate, were defined as reversible reactions and other reaction steps were defined as irreversible processes. Using the experimental data reported by Luo et al. (2009), the values predicted in this study were compared with the previous model reported by Luo et al. (2009) using both the average absolute deviation (AAD) and root mean square deviation (RMSD). The AAD and RMSD of the new model were 31% and 33% lower than that of the existing one, respectively. Overall, the proposed model for glycerol chlorination is superior to the previous model.

Corrosion analysis of a heat‐exchanger in epichlorophydrin production process

AbstractThe failure of E230 heat‐exchanger in the production of epichlorophydrin (ECH) form dichloropropanol (DCP) was analyzed and material solutions are recommended. The analysis indicates that the combined effect of stress corrosion cracking (SCC) and dissolution of HCl and HClO in the DCP mixture solution in the E230 heat‐exchanger chamber to the tube surface and chamber wall contributes to the failure of heat‐exchanger tubes and the perforation of E230 heat‐exchanger chamber. It is recommended to reduce the content of Cl– in the DCP mixture solution and to increase its pH. Titanium, Type 316L stainless steel (SS), and electroless Ni‐P coating can be considered as the candidate materials. Also, the process can be divided into two series step with one step heating the temperature from 30°C to 60°C, and the other step heating the temperature from 60°C to 90°C. For the lower temperature step, the Type 316L SS or electroless Ni‐P coating can be used. For the higher temperature step, Titanium can be applied. Periodic cleaning of the tube surface and chamber inner surface deposit is necessary. Intensifying the in‐service inspection and monitoring is also required.

Design of a Reactive Distillation Column for Direct Preparation of Dichloropropanol from Glycerol

In the present study, a reactor design for the direct preparation of dichloropropanol (DCP) from glycerol (GLY) is presented. As an optimum design, a reactive distillation (RD) column in which the second chlorination of GLY occurs during the direct preparation of DCP from GLY has been introduced. Using a simple equilibrium mathematical model of RD, a pilot plant scale column is designed. Furthermore, the whole preparation process of DCP from GLY used the optimum RD column as the central unit is simulated by using an advanced software tool, namely ASPEN PLUS. The pilot plant realization of the whole preparation process is presented and its results are compared with the theoretical prediction. On the basis of the pilot plant data and simulated results, a new technology of DCP production has been designed.

Regeneration of H3PW12O40 catalyst in the direct preparation of dichloropropanol (DCP) from glycerol and hydrochloric acid gas

Methods for regenerating H3PW12O40 catalyst in the solvent-free direct preparation of dichloropropanol (DCP) from glycerol and hydrochloric acid gas were investigated. Regenerated H3PW12O40 catalyst was then applied to the solvent-free direct preparation of DCP. In the solvent-free direct preparation of DCP, selectivity for DCP over H3PW12O40 catalyst regenerated by method I (recovery of solid H3PW12O40 catalyst by evaporating homogeneous liquidphase product solution) significantly decreased with increasing recycling run, while that over H3PW12O40 catalyst regenerated by method II (regeneration of H3PW12O40 catalyst by oxidative calcination of solid product recovered by method I) was slightly decreased with no significant catalyst deactivation with respect to recycling run. On the other hand, selectivity for DCP over H3PW12O40 catalyst regenerated by method III (regeneration of H3PW12O40 catalyst by recrystallization and subsequent oxidative calcination of solid product recovered by method II) was the same as that over fresh catalyst without any catalyst deactivation with respect to recycling run. Thus, method III was found to be the most efficient method for the regeneration of H3PW12O40 catalyst.

Direct preparation of dichloropropanol from glycerol and hydrochloric acid gas in a solvent-free batch reactor: Effect of experimental conditions

Solvent-free direct preparation of dichloropropanol (DCP) from glycerol and hydrochloric acid gas was carried out in a batch reactor with a variation of reaction conditions (agitation speed, reaction time, reaction temperature, and reaction pressure), amount of H3PW12O40 catalyst, and amount of water absorbent (silica gel blue). The reaction was conducted at high agitation speed in order to avoid mass transfer limitation between glycerol and hydrochloric acid gas. In the direct preparation of DCP from glycerol and hydrochloric acid gas, DCP formation was increased with increasing reaction time, reaction temperature, and reaction pressure. Chlorination of glycerol occurred via the following consecutive reaction steps: glycerol→monochloropropanediol (MCPD)→dichloropropanol (DCP)→trichloropropane (TCP). Reaction rate decreased in the order of first-step reaction>second-step reaction>third-step reaction. The presence of H3PW12O40 catalyst and water absorbent (silica gel blue) enhanced the formation of DCP. DCP formation was increased with increasing the amount of H3PW12O40 catalyst and water absorbent (silica gel blue). Strong Bronsted acid site of H3PW12O40 catalyst and water removal from the reaction system favorably served in improving DCP formation.

Effect of reaction conditions on the catalytic performance of H3PW12O40 heteropolyacid catalyst in the direct preparation of dichloropropanol from glycerol in a liquid-phase batch reactor

Direct chlorination of glycerol to dichloropropanol (DCP) was conducted in a liquid-phase batch rector using homogeneous H3PW12O40 heteropolyacid (HPA) catalyst. The effect of reaction conditions (reaction time, reaction pressure, reaction temperature, and catalyst amount) on the catalytic performance of H3PW12O40 in the direct preparation of DCP from glycerol was examined. The optimum reaction pressure and reaction temperature were found to be 10 bar and 130 °C, respectively. The reaction temperature was more crucial than the reaction pressure in improving the selectivity to DCP. Selectivity to DCP increased with increasing reaction time and with increasing catalyst amount. Acid sites of H3PW12O40 catalyst favorably devoted to the chlorination of glycerol. H3PW12O40 served as an efficient catalyst in the direct preparation of DCP from glycerol under the mild reaction conditions.

Solvent-free direct preparation of dichloropropanol from glycerol and hydrochloric acid gas in the presence of H3PMo12−W O40 catalyst and/or water absorbent

Solvent-free direct preparation of dichloropropanol (DCP) from glycerol and hydrochloric acid gas was carried out in the presence of H3PMo12−XWXO40 (X = 0, 3, 6, 9, and 12) heteropolyacid (HPA) catalyst and/or water absorbent. Acid strength of the HPA catalyst played an important role in determining the catalytic performance in the solvent-free direct preparation of DCP. Water formed during the reaction retarded the formation of DCP. Absorption of water using silica gel blue (water absorbent) during the reaction greatly enhanced the formation of DCP. A combination of HPA catalyst with silica gel blue resulted in further enhancement of DCP formation.

Catalytic activity of H3PMo12−XWXO40 and H6P2MO18−XWXO62 heteropolyacid (HPA) catalysis in the direct preparation of dichloropropanol (DCP) from glycerol

H3PMo12−XWXO40 (X=0−12) and H6P2Mo18−XWXO62 (X=0−18) heteropolyacid catalysts were applied to the direct preparation of dichloropropanol from glycerol. Acid properties of the catalysts were determined by NH3-TPD measurements. The catalytic performance increased with increasing acid strength of the catalyst. Among the catalysts tested, the H3PW12O40 catalyst of highest acid strength showed the best catalytic performance.

Direct preparation of dichloropropanol (DCP) from glycerol using heteropolyacid (HPA) catalysts: A catalyst screen study

Abstract Direct preparation of dichloropropanol (DCP) from glycerol was carried out in a batch reactor using H3PMo12−XWXO40 (X = 0–12), H4SiMo12−XWXO40 (X = 0–12), H3+XPW12−XVXO40 (X = 0–3), and H3+XPMo12−XVXO40 (X = 0–3) heteropolyacid (HPA) catalysts. Acid properties of the HPA catalysts were then determined by NH3-TPD measurements in order to correlate the catalytic activity with the acid property of the catalysts. The acid strength of the HPA catalyst played a key role in determining the catalytic performance in the reaction. The selectivity for DCP increased with increasing acid strength of the catalyst. Among the catalysts tested, H3PW12O40 with the highest acid strength showed the best catalytic performance.

Improved Abrasion Resistance Through Internal Lubrication

, The cross-linking reaction of cellulose with lauroyl and stearoyl ester is described. With increasing number of carbon atoms in the ester substituent, the reactivity and wet crease recovery decreased. There is an improvement in tear and abrasion resistance and, with stearoyl ester, a remarkable improvement (5 to 20 times) in flex abrasion resistance. The tear resistance, however, is improved only to the extent of 10% to 50%. By using a modified microscopic count technique and a polarizing microscope, it is shown that the cellulose is cross-linked. The degree of insolubility in cuprithylene diamine is proportional to the degree of cross-linking. Bulk scale application of stearoyl dichloropropanol (DCP) to two fabrics, viz, medium and superfine poplins, has been done. An improvement in abrasion resistance of about 500% to 800% and tear resistance of 20% to 50% has been recorded. The finish is stable to mild laundering, boiling 0.5 N aqueous caustic soda, and boiling 0.5% non-ionic detergent. However, boiling solutions of soap (0.5%) and soda (0.2%) hydrolyze the ester-link, though the cross-linking is still unaffected. The treated fabrics are suitable base materials for wash-wear treatment and it is possible to obtain wash-wear fabrics with abrasion resistance equivalent to or higher than the starting material. Some data on field wear trials of SDCP-treated fabrics are presented and discussed. It is concluded that the idea of providing internal or built-in lubrication by the use of three carbon cross links, with a bulky substituent at the center, may open up a new approach to enhance the abrasion resistance of cotton and other cellulosic textiles.