Vacuum swing adsorption (VSA) capture of CO 2 from flue gas streams is a promising technology for greenhouse gas mitigation. In this study we use a detailed, validated numerical model of the CO2VSA process to study the effect of a range of operating and design parameters on the system performance. The adsorbent used is 13X and a feed stream of 12% CO 2 and dry air is used to mimic flue gas. Feed pressures of 1.2 bar are used to minimize flue gas compression. A 9-step cycle with two equalisations and a 12-step cycle including product purge were both used to understand the impact of several cycle changes on performance. The ultimate vacuum level used is one of the most important parameters in dictating CO 2 purity, recovery and power consumption. For vacuum levels of 4 kPa and lower, CO 2 purities of >90% are achievable with a recovery of greater than 70%. Both purity and recovery drop quickly as the vacuum level is raised to 10 kPa. Total power consumption decreases as the vacuum pressure is raised, as expected, but the recovery decreases even quicker leading to a net increase in the specific power. The specific power appears to minimize at a vacuum pressure of approximately 4 kPa for the operating conditions used in our study. In addition to the ultimate vacuum level, vacuum time and feed time are found to impact the results for differing reasons. Longer evacuation times (to the same pressure level) imply lower flow rates and less pressure drop providing improved performance. Longer feed times led to partial breakthrough of the CO 2 front and reduced recovery but improved purity. The starting pressure of evacuation (which is not necessarily equal to the feed pressure) was also found to be important since the gas phase was enriched in CO 2 prior to removal by vacuum leading to improved CO 2 purity. A 12-step cycle including product purge was able to produce high purity CO 2 (>95%) with minimal impact on recovery. Finally, it was found that for 13X, the optimal feed temperature was around 67°C to maximize system purity. This is a consequence of the temperature dependence of the working selectivity and working capacity of 13X. In summary, our numerical model indicates that there is considerable scope for improvement and use of the VSA process for CO 2 capture from flue gas streams.

Antagonism of the human A(2A) receptor has been implicated as a point of therapeutic intervention in the alleviation of the symptoms associated with Parkinson's disease. This is thought to occur, at least in part, by increasing the sensitivity of the dopaminergic neurons to the residual, depleted levels of striatal dopamine. We herein describe a novel series of functionalized triazolo[4,5-d]pyrimidine derivatives that display functional antagonism of the A(2A) receptor. Optimization of these compounds has resulted in improvements in potency, selectivity, and the pharmacokinetic properties of key derivatives. These efforts have led to the discovery of 60 (V2006/BIIB014), which demonstrates strong oral activity in commonly used models of Parkinson's disease. Furthermore, this derivative has shown excellent preclinical pharmacokinetics and has successfully completed phase I clinical studies. This compound is presently undergoing further clinical evaluation in collaboration with Biogen Idec.

Poly­(pentadecalactone)-b-poly­(l-lactide) (PPDL-b-PLLA) diblock copolymers were prepared via the organic catalyzed ring-opening polymerization (ROP) of l-lactide (l-LA) from PPDL macroinitiators using either 1,8-diazabicyclo[5.4.0]­undec-7-ene (DBU) or 1,5,7-triazabicyclo[4.4.0]­dec-5-ene (TBD). Synthesis of PLLA blocks targeting degrees of polymerization (DP) up to 500 were found to yield diblock copolymers with crystalline PPDL and PLLA segments when TBD was used as the catalyst. The synthesis was further improved in a one-pot, two-step process using the same TBD catalyst for the synthesis of both segments. The application of these diblock copolymers as a compatibilizing agents resulted in homogenization of a biobased PLLA/poly­(ω-hydroxytetradecanoate) (90:10) blend upon a melt-process, yielding enhanced material properties.

We report the use of an organic catalyst system capable of switching between active and dormant propagating states during the ROP of cyclic monomers. While the ROP of both ε-caprolactone and trimethylene carbonate proceeds under nitrogen, the simple addition of CO2 results in a dormant “off” state. Cycling between atmospheres provides the ability to regulate the molecular weights of the resulting polymers without appreciable loss of catalytic activity for several “on/off” cycles.

Shape-memory polymers (SMPs) are a class of stimuli-responsive materials that have attracted tremendous attention in various applications, especially in the medical field. While most SMPs are thermally actuated, relating to a change of thermal transition (e.g., melting temperature), SMPs that can be actuated upon exposure to light are emerging. Recently, there has been new interest into multiple stimuli-responsive SMPs in order to cover the range of applications for these smart materials. In this work, poly­(ester-urethane)­s (PURs) made of heating-responsive poly­(ε-caprolactone) (PCL) segments of various degrees of crystallinity and photoresponsive N,N-bis­(2-hydroxyethyl) cinnamide (BHECA) monomer were successfully prepared using reactive extrusion technology to design dual-stimuli-responsive SMPs (DSRSMP). In order to tune the SMP properties (temperature or light), the crystallinity of the PCL segment was finely adjusted by the copolymerization of ε-caprolactone with para-dioxanone in bulk at 160 °C using tin­(II) octoate. The resulting polyester segments were then coupled with BHECA using n-octyl diisocyanate at 130 °C. The SMP properties of resulting PURs were correlated with DSC and DMTA measurements. Further addition of di- and tetracinnamate PCL segments into these SMPs was also studied in order to enhance the photoactuated SMP properties.

fast, solution-adaptive finite-volume technique for the simulation of a single adsorption step for a variety of boundary conditions was described. In this study, we apply this method to the simulation of nonisothermal PSA/VSA cycles of general complexity. Using successive substitution, stage-wise node refinement, and control algorithms, rapid cyclic steady state can be achieved even for problems with very long dynamics. We illustrate the advantages of node refinement as a useful tool for accelerating convergence to cyclic steady state. Simultaneous incorporation of control techniques into the successive substitution framework allows for rapid convergence of the PSA process to design specifications. We compare the results of our simulator to experimental data for a two-bed VSA process and find good agreement in pressures, flows, and temperatures.

This paper investigates the thermal profiles that arise in oxygen VSA, which is a prominent example of a PSA bulk gas separation process. Experimentally, it is demonstrated that the severe axial thermal profile or "cold spot" that frequently characterizes oxygen VSA can only arise if there are multilayered adsorption beds or if there are readily adsorbed trace components (such as water) that create a de facto multilayered bed. A qualitative explanation is offered to explain how this cold spot is formed. This paper also details a technique for predicting the penetration of a water-loaded zone into an oxygen VSA adsorption bed based on the method of characteristics. The results of this technique compare well with experimental and numerically simulated results. Finally, this paper demonstrates that a water-loaded zone and an inert zone of activated alumina result in very similar cyclic steady-state thermal profiles, even though the transient behaviors are markedly different.

The synthesis and application of a dibenzyl-functionalized bispidine, in combination with 1-(3,5bis(trifluoromethyl)phenyl)-3-cyclohexylthiourea (TU) co-catalyst, has been demonstrated to be an excellent catalyst for the controlled ring-opening polymerisation (ROP) of lactide and cyclic carbonate monomers. Notably, the polymerisation proceeds with negligible transesterification or epimerisation, with the polymerisation of stereopure L-lactide affording highly crystalline poly(lactide) with a T m of 156 C. ROP of racemic lactide results in the observation of a modest degree of stereocontrol such that the probability of isotactic enchainment, P m ¼ 0.74. Comparison of a range of alternative hydrogen bond donor co-catalysts revealed that TU displayed the highest polymerisation rates in combination with the dibenzyl-functionalized bispidine.