An economic performance evaluation framework for hydrogen production (HP) plants with integrated catalytic membrane reactor (CMR) modules is presented (HP-CMR) in light of their enhanced environmental performance prospects. A detailed comprehensive Net Present Value (NPV) model is first developed in order to assess the economic viability of HP-CMR plants, while irreducible sources of market and regulatory uncertainty are identified and their effect on the plant's economic performance is explicitly taken into account through Monte-Carlo techniques. As a result, the proposed economic performance evaluation framework for an HP-CMR plant allows the derivation of distribution profiles of economic performance outcomes rather than single-point value estimates that often lead to unsatisfactory valuation assessments by overlooking significant uncertainty effects over the plant's lifetime. Within the above framework, the HP-CMR plant is comparatively assessed against the conventional HP plant with and without Carbon Capture and Sequestration (CCS) systems. It is shown that future regulatory action on CO 2 emissions leads to comparatively appealing distribution profiles of economic performance outcomes for HP-CMR plants in the presence of uncertainty, thus offering a window of opportunity for this new technology option to emerge as a viable one for hydrogen production in a carbon-constrained world. Finally, the provision of a set of incentives is considered that could potentially facilitate the demonstration stage of the HP-CMR technology option on the commercial scale.

The present study encompasses the results of a comprehensive performance assessment of different pilot-scale Pd/Alloy composite asymmetric membranes under long-term coal-derived syngas atmosphere testing. The membranes were developed and tested first at the CIMS-WPI laboratory under pure H 2 and later at NCCC under a mixture of N 2 /H 2 and H 2 enriched syngas coming from a TRIG TM gasification system. Thirteen membranes were examined for 4275 h and classified in four types: Pd, Pd/Au, Pd/Pt and Pd/Au/Pt membranes. Their respective H 2 permeance and purity profiles, permeance difference under pure hydrogen and syngas conditions as well as stability of operation were assessed. The membranes showed good stability in syngas although exhibiting an initial drop in permeance when compared to that under pure hydrogen. Pure Pd membranes displayed the highest permeability, but showed pinholes after being exposed to syngas. Pd/Pt membranes showed a reduced permeance drop under syngas conditions, indicating sulfur resistance properties. Furthermore, Pd/Au/Pt membranes, presented for the first time in the literature, displayed stable permeance and purity profile. The inhibition of the initial permeance drop and the long-term operation of these ternary membranes were demonstrated. Finally, Pd/Au membranes were shown to display the most stable permeance and purity characteristics. In this case, the initial permeance drop was significantly reduced, exhibiting the lowest decline amongst all cases considered. It is hypothesized that Au may act as a patch paste blocking defects on the Pd layer.

Bio-derived polyethylene furanoate (PEF) has recently gained attention as a sustainable alternative to polyethylene terephthalate (PET), amidst environmental concerns over fossil fuel depletion. Herein, we outline a computational approach to investigate the tenfold difference in barrier properties between the two materials, using a statistically robust methodology to predict diffusion coefficients from molecular dynamics simulation. Oxygen diffusion was predicted to a high level of accuracy, at 3.24 × 10–8 and 2.88 × 10–9 cm2 s–1 for PET and PEF, respectively (D experimental = 1.16 × 10–8 and 1.04 × 10–9 cm2 s–1). Simulations quantifiably demonstrated the contributions of ring-flipping chain dynamics on oxygen diffusion, and novel Monte Carlo techniques revealed atomistic insights into the mechanism by which this occurs. Areas of accessible volume within the polymer matrix were seen to converge to facilitate lateral oxygen displacement. Infrequent convergences in PEF, due to subdued polymer chain dynamics and higher system density, accounted for the slower oxygen diffusion relative to PET.

Culture contamination, end-product toxicity, and energy efficient product recovery are long-standing bioprocess challenges. To solve these problems, we propose a high-pressure fermentation strategy, coupled with in situ extraction using the abundant and renewable solvent supercritical carbon dioxide (scCO2), which is also known for its broad microbial lethality. Towards this goal, we report the domestication and engineering of a scCO2-tolerant strain of Bacillus megaterium, previously isolated from formation waters from the McElmo Dome CO2 field, to produce branched alcohols that have potential use as biofuels. After establishing induced-expression under scCO2, isobutanol production from 2-ketoisovalerate is observed with greater than 40% yield with co-produced isopentanol. Finally, we present a process model to compare the energy required for our process to other in situ extraction methods, such as gas stripping, finding scCO2 extraction to be potentially competitive, if not superior.