การศึกษาเพื่อความเข้าใจอย่างชัดแจ้งของการแตกสลายของ โมโนเอทานอลามีนในสารละลายน้ำ ระหว่างการจับก๊าซคาร์บอนไดออกไซด์จากปล่องก๊าซของโรงไฟฟ้าพลังงาน: วิธีวิเคราะห์จลนศาสตร์ของการแตกสลาย และวิธีป้องกันการแตกสลายโดยใช้สารยับยั้ง

Thesis (Ph.D) -- Chulalongkorn University, 200

Mechanism of formation of heat stable salts (HSSs) and their roles in further degradation of monoethanolamine during CO2 capture from flue gas streams

AbstractThe roles of HSS induced acid products of MEA degradation were evaluated. The results show that formic and acetic acids, formed as a result of MEA oxidation, exist in 2 forms in equilibrium; namely, salts and amides. Specifically, these are formate and acetate, and N-(2-hydroxyethyl)formamide and N-(2-hydroxyethyl)acetamide, respectively. Glycolic acid, also formed due to MEA oxidation, is stable and exists mostly bonded with MEA to produce the glycolate HSS. Its amide is unstable, hydrolyzing back to glycolate and MEA. Oxalic acid was found as a reactive intermediate that mostly decomposed to formic acid, which in turn produced a stable N-(2-hydroxyethyl)formamide. Oxalic acid amide (N-(2-hydroxyethyl)oxamide) could also be formed but its formation was considered a minor route compared with the decomposition route. Succinic acid formed a stable imide (N-(2-hydroxyethyl)succinimide) through an intermediate amide (N-(2-hydroxyethyl)succinamide)

Investigation of degradation inhibitors on CO2 capture process

AbstractIn this study we have used sodium sulfite (Na2SO3), potassium sodium tartrate tetrahydrate (KNaC4H4O6⋅4H2O), ethylenediaminetetraacetic acid (EDTA), and hydroxylamine (NH2OH) to effectively inhibit O2-SO2 induced degradation of amines such as monoethanolamine (MEA) during CO2 capture from flue gases (i.e. the degradation systems of MEA-O2-SO2-H2O-CO2). The ranges of experimental conditions were such as to duplicate the extremes normally encountered in a typical CO2 capture process in a coal fired power plant. MEA concentration, O2 concentration, SO2 concentration, CO2 concentration and degradation temperature were respectively in the range of 3–7 kmol/m3, 6–100%, 0–196 ppm, 0–0.52 loading, and 393 K. There were optimum concentrations of these inhibitors that best prevented the degradation; namely, 0.05, 0.01, 0.0025, and 0.025 kmol/m3 respectively for Na2SO3, NaKC4H4O6⋅4H2O, EDTA, and NH2OH. Outside these concentrations the inhibitors were not very effective. The blend of Na2SO3-KNaC4H4O6⋅4H2O was the most effective inhibitor either in the absence or presence of CO2. Based on the evaluation of the inhibition mechanisms, Na2SO3 works as an O2 and SO2 scavenger, while KNaC4H4O6⋅4H2O, EDTA, and NH2OH function as radical scavengers. It was also observed that CO2 alone works on the basis of the salting out effect whereby CO2 goes into the aqueous amine solution in preference to O2 and SO2

Study of Physical and Chemical Resistance of Elastomers in Aqueous MEA and MEA+CO2 Solutions during the Carbon Dioxide Absorption Process

AbstractA study was conducted to evaluate the resistance of raw EPDM, natural rubber (NR), isobutylene isoprene rubber (IIR) and styrene butadiene rubber (SBR) to amines in terms of mass and chemical changes in an amine-based CO2 capture environment made up of aqueous solutions of 3–7M MEA with 0–0.5mol CO2/mol MEA. The test for each condition lasted for 30 days at 40°C. The results showed that SBR and NR had poor chemical resistance leading to formation of amides on their surfaces and resulting in high mass change. In contrast, EPDM and IIR had insignificant mass and chemical structure changes. The performance of commercial EPDM and IIR were then further studied and compared against PTFE, using aqueous 5M MEA and with 0.5mol CO2/mol MEA at 40 and 120°C each for 30 days. Resistance was measured in terms of mass, hardness, and tensile strength changes. The results showed that PTFE was compatible with the solution at both temperatures. For EPDM and IIR at 40°C, the changes in mass, hardness, and tensile strength were negligible while at 120°C, these changes were very significant. The implication is that PTFE can be used in any part of the process while EPDM and IIR can only be used in low-temperature sections