Ring-opening polymerization

Ring-opening polymerization is defined by IUPAC (Penczek, S., Moad, G. (2008). Glossary of the terms related to kinetics, thermodynamics, and mechanisms of polymerization. (IUPAC Recommendations 2008), Pure and Applied Chemistry, 80(10), 2163–2193) as (cit.) “Ring-opening polymerization (ROP): Polymerization in which a cyclic monomer yields a monomeric unit that is either acyclic or contains fewer rings than the cyclic monomer”. The large part of the resulting polymerizations is living/controlled; practically all belong to chain polymerizations. After the introduction, providing basic information on chain polymerizations, the paper presents the concise overview of major classes of monomers used in ROP, including cyclic ethers, esters, carbonates, and siloxanes as well as cyclic nitrogen, phosphorus, and sulfur containing monomers. There are discussed also thermodynamics, kinetic polymerizability, and major mechanisms of ROP. Special attention is concentrated on polymers prepared by ROP on industrial scale.

Low permeability coal seam gas productivity enhancement by cyclic nitrogen injection technique (an adsorption simulation study)

Coal seam gas (CSG) usually contains high levels of methane, which is mostly in the adsorbed state on micropores. For coal that is not highly permeable, stimulation may be required to enhance productivity. In this study, we propose a new technique to increase near wellbore productivity in tight CSG. This technique comprises three stages: injection, soaking and production. Firstly, nitrogen is introduced to the target formation while maintaining high reservoir pressure. Next, the well is shut for a period of time before the gases are flown back to the surface. The technique is based on competitive adsorption of methane and nitrogen during the shut-in period, which yields pressure build-up. Hence, with this combination of desorption, the coal matrix shrinks and permeability eventually increases. The proposed technique was tested by adsorption simulation at core scale. The model was constructed for crushed samples and the extended Langmuir isotherm and micro–macro kinetics models were applied in ASPEN adsorption software. Tight coal was then simulated with different porosity and sorption characteristics. Finally, we used the stress-sensitive permeability model Palmer–Mansoori to predict permeability changes. The results show that permeability is improved based on pressure variations. We observed 10% pressure increments with greater than 150% permeability enhancement. The model indicates the feasibility of the newly proposed technique to produce the ‘unproducible’. However, more experimental and simulation studies at a reservoir scale are needed to fully confirm the technique.

Study of Di- and Polyamines as Activators in the Hot Potash Process for CO2 Capture

An alarming rise in the atmospheric level of CO2 beyond safe limits has posed an immediate threat to mankind. It has become necessary to look for new economic processes for its capture and for options that can lead to reduction in the cost of existing processes. Hot potassium carbonate is one of the most viable processes. Efforts are continuously being made to improve on the capacity and rate of absorption of this solvent primarily by the use of activators. The latest activators in this category belong mostly to amines like piperazine and other cyclic nitrogen compounds. However, their study so far has been very haphazard. The first systematic study on alkanol monoamine activators was initiated and reported earlier by the authors. This paper extends the study and discusses the effect of some acyclic and cyclic diamines and polyamines as activators on absorption and regeneration of CO2 in K2CO3 solution. The effect of the cyclic or acyclic nature of the molecule, number of substituents, their chemical nature and their spatial arrangement was investigated. The parameters studied for this effect are rich and lean amine loading of CO2, CO2 regenerated and pKa of activators. Interestingly, it was observed that the bulkiness and spatial arrangement of substituents is the most dominant factor. An unsubstituted cyclic diamine (piperazine) performs best in enhancing the absorption capacity of solvent whereas diethylenetriamine is the best in enhancing rate of absorption. The study reveals no specific correlation of pKa value of the amines with their effect as activator.

Physical Methods in Chemistry Investigations of the Chemistry Institute of ASM

The following classes of compounds are presented: terpenes, cyclic nitrogen compounds, dioximates, carboxylates etc., which have been studied with the participation of experts on physical methods of research - IR, UV-Vis, Atomic, Mössbauer spectroscopy, as well as Mass-spectrometry and Nuclear Magnetic Resonance in the IC ASM. Also, a number of significant scientific results obtained in collaboration of chemists and specialists in physical methods are described.