This article provides results of the in situ monitoring of carbon dioxide (CO₂) removal under high pressure. An aqueous solution of methyldiethanolamine (MDEA) promoted by piperazine (PZ) for absorption rate acceleration was used. This system is promising for natural gas purification. A predictive statistical model was built using the chemometrics method and measurements of density, pH, conductivity, sound velocity, refractive index, and Near Infra-Red (NIR) spectroscopy. The CO₂ capture rate ranged from 60% up to 96% at pressures in the absorber column ranging between 15 and 20 bar. The liquid stream composition was monitored at the low pressure part of a pileline at a location before a compressor stage. The concentrations of MDEA, PZ, and CO₂ were predicted in-line using different sets of the measurement devices during 3 days of the measurement campaign. The developed approach allowed for prediction of the concentrations with accuracies of 0.7% for MDEA, 0.4% for PZ, and 2.5% for CO_2.@en

This work covers the development of robust and stable in time poly[1-(trimethylsilyl)-1-propyne] (PTMSP) thin film composite (TFC) membranes with high CO₂ permeance for its application in high pressure/temperature gas-liquid membrane contactors used for amine-based solvents regeneration. For the first time, a novel technique of two-layers coating was proposed and successfully implemented to apply thin top-layer on microfiltration support by adjusting PTMSP solubility in organic solvents. By using different catalytic systems such as NbCl₅ and TaCl₅/TIBA, it was possible to synthesize two polymer samples ("PTMSP-Nb" and "PTMSP-Ta"), which are insoluble and soluble in hexane, respectively. The first intermediate layer made of "PTMSP-Nb" was cast on the microfiltration porous support from a toluene solution in order to form a PTMSP-coated porous support. The solution of "PTMSP-Ta" in n-hexane was used for subsequent formation of a thin defect-free selective layer (second layer). By using two commercial polymeric (MFFK-1) and metal-ceramic (MC) supports with high surface porosity of 85% and 60%, respectively, it was possible to fabricate the tailor-made TFC membranes "PTMSP/MFFK" (top-layer - 0.5μm) and "PTMSP/MC" (top-layer - 1.2μm) with an initial CO₂ permeance of 50 and 36.3m³(STP)/(m²hbar), respectively, and CO₂/N₂ selectivity of 3.5. A preliminary conditioning of the PTMSP/MC membrane at 100°C for 100h in air was applied for the accelerated relaxation of PTMSP top layer. The resulting robust PTMSP/MC TFC membranes still provided a high CO₂ permeance of 1.6m³(STP)/(m²hbar) (~600GPU) without a noticeable decline of membrane performance within the long-term gas permeation testing (at least 250h) at 100°C. The PTMSP/MC membranes were further successfully utilized in HPT MGD for regeneration of 50wt% methyldiethanolamine (MDEA) at elevated temperature (100°C) and pressures (up to 30bar). A stable TFC membrane performance was demonstrated and no solvent leakage through the membranes was observed.

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The Helix reactor is highly suited for precise reaction control based on good hydrodynamics. The hydrodynamics are controlled by the Dean vortices, which create excellent heat transfer properties, approach plug flow and avoid turbulence. The flexibility of this reactor has been demonstrated using a very exothermic, temperature sensitive alkylation reaction, a mechanically delicate emulsion polymerisation reaction and a precipitation reaction. It was demonstrated that the highly exothermic alkylation reaction could be controlled such that no side reactions occured. In the case of the emulsion polymerisation reaction the gentle mixing conditions of the Helix reactor were used to control the particle size and size distribution. Also for the precipitation reaction it was possible to obtain a narrow particle size distribution and to control the particle size. It can be concluded that the helix reactor is a versatile tool to perform reactions that are typically batch wise operated in a continuous way, and thereby reducing costs and improving safety and quality.

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