Kinetic hydrate inhibitors (KHIs) are applied in oil and gas fields to prevent gas hydrate formation, most often in cold subsea flow lines. The main component in industrial KHI formulations is a water-soluble polymer with many amphiphilic groups of which the hydrophilic part is most commonly the amide functional group. In the last decade, we have investigated polyamine oxides as alternatives to polyamides due to the strong hydrogen bonding of the amine oxide group. Here, we report the KHI performance of maleic and methacrylic homopolymers with dialkylamine and dialkylamine oxide pendant groups. Performance screening experiments were conducted under high pressure with a Structure II-forming natural gas mixture in steel rocking cells using the slow (1 °C/h) constant cooling test method. Polymers with dibutylamine groups gave much better KHI performance than polymers with dimethylamine or diethylamine groups. Polyamines formed from polymaleic anhydride reacted with 3-(dibutylamino)-1-propylamine (DBAPA) or 2-(dibutylamino)-ethanol (DBAE) gave good water solubility and good KHI performance, probably due to self-ionization between the dibutylamino and carboxylic acid groups. The lack of self-ionization for the methacryl homopolymers of DBAPA and DBAE explains why these polymers are not water-soluble. Oxidation of the maleic or methacryl polyamines to polyamine oxides gave water-soluble polymers with good compatibility with brines (0.5-7.0 wt % NaCl), but only the DBAPA-based polyamine oxides gave improved KHI performance compared to the polyamines. Poly(3-(dibutylamino oxide)-1-propyl methacrylamide) gave a similar performance to commercial -vinyl pyrrolidone:-vinyl caprolactam 1:1 copolymer and without a cloud point in deionized water up to +95 °C.
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http://dx.doi.org/10.1021/acsomega.2c05713 | DOI Listing |
Heliyon
January 2025
Mechanics Laboratory, Doctoral Training Unit in Engineering Sciences, Doctoral School of Fundamental and Applied Sciences, University of Douala, P.O. Box: 2701, Douala, Cameroon.
This study focuses on the influence of the partial substitution of cement by Cameroonian corn stover ash (CCSA) on the physical and mechanical behavior of concrete. For this, as materials used, one has first the corn stovers coming from the Bandjoun town in the Koung-khi division, in the West region of Cameroon, which are used to obtain the ashes, while the sand used, came from the Sanaga River in the coastal region of Cameroon. In order to obtain the CCSA, the corn stover is calcined in an oven at 600 °C for 6 h and then characterized; the characterization included infrared spectrometry, X-ray fluorescence spectrometry, fineness of grinding, and absolute density.
View Article and Find Full Text PDFMali Med
November 2024
Service d'hépato-gastro-entérologie du CHU de Cocody (Côte d'Ivoire).
Objective: To evaluate the prediction of esophageal varices by SEF measured by fibroscan® in cirrhotic patients followed at Cocody CHU.
Method: This was a cross-sectional study conducted at HGE at Cocody CHU for 5 years. Included records of compensated cirrhotics followed at HGE.
ACS Omega
August 2024
Department of Pharmaceutical Engineering, Faculty of Engineering, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama 939-0398, Japan.
Current commercial kinetic hydrate inhibitors (KHIs) are all based on water-soluble polymers with amphiphilic alkylamide or lactam groups. The size and shape of the hydrophobic moiety are known to be critical for optimum KHI performance. Proteins and peptides represent an environmentally friendly alternative, especially as bioengineering could be used to manufacture a product predetermined to have optimum KHI performance.
View Article and Find Full Text PDFFront Oncol
June 2024
Japan Community Heathcare Organization, Osaka Hospital, Osaka, Japan.
Background: Regorafenib improves overall survival (OS) of patients with advanced progressive gastrointestinal stromal tumors (GISTs) after standard chemotherapy in phase III trials in the 3rd-line setting. This large-scale, prospective observational study evaluated the safety and effectiveness of regorafenib in Japanese patients with GIST in a real-world clinical setting.
Methods: Patients with GIST received oral regorafenib at a maximum daily dose of 160 mg for weeks 1-3 of each 4-week cycle (dose could be modified at investigator's discretion).
Front Chem
May 2024
Chemical Polymeric and Petrochemical Technology Development Research Division, Research Institute of Petroleum Industry, Tehran, Iran.
Kinetic hydrate inhibitor laboratory testing before field application is one of the key priorities in the oil and gas industry. The common induction-time-based technique is often used to evaluate and screen for kinetic hydrate inhibitors (KHIs). However, the main challenge relates to the stochastic nature of hydrate nucleation observed in fresh systems, which often results in scattered data on hydrate formation with unacceptable uncertainties.
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