Comparison of Porosity Change Due to Geochemical Reaction between Samples from High CO2 Field and Depleted Field

When developing a high CO2 field, oil and gas companies must consider the best and most economical carbon capture and storage (CCS) plan. After considering the distance of the storage site and storage capacity, PETRONAS has identified 2 carbonate fields, known as X Field and N Field in East Malaysia as the potential CO2 storage site. Interestingly, both fields are different, as X field is a high CO2 green field, while N field is a depleted gas field. The research team’s initial hypothesis is that N Field would have more severe geochemical reaction between CO2, brine and carbonates compared to X Field, since X field is already saturated with CO2. In order to test the hypothesis, samples from these two fields were selected to undergo static batch reaction analysis, and changes in porosity were determined using Digital Core Analysis (DCA). Both X and N fields are carbonate gas fields, with aquifer zone located below gas zones. The aquifer zones are the preferable CO2 injection zone because the deeper the zone, the longer it will take for the plume migration to happen. For static batch reaction analysis, samples each field were selected from the aquifer zone. After Routine Core Analysis (RCA) and Quality Control (QC), the samples were scanned under the high resolution microCT scan, before they were saturated into the respective synthetic brine. After saturation is completed, both brine and samples were placed inside a batch reactor, where the reactor’s pressure and temperature are set according to the field’s pressure and temperature. Once stabilized, the supercritical CO2 is injected into the brine, and was left for 45 days with constant observation. After aging with supercritical CO2, the samples were then scanned under microCT scan once again, using the same resolution, before being analysed via image processing software. Using registration algorithm software, both pre and post CO2 aging images were overlapped and subtracted digitally. The difference images were analyzed to determine the change in porosity. Samples from X Field has around 1% p.u. increase in porosity, while samples from N field shows increment of 2% p.u. porosity. While N field (depleted field) has higher reaction compared to X field (high CO2) field as per hypothesis, the difference is very minimal, which is much less than expected. The usage of DCA in the analysis enabled the team to determine minute changes that were happening during CO2 batch reaction. Without DCA, the 1% changes usually regarded as equipment’s error margin. The next step would be modelling, where the lab results will be upscaling into field scale, for modelled longer period of time. Hence, although the porosity changes between X and N field are very small under laboratory condition, it can have greater impact in field scale.

Immobilization of β-Glucosidase over Structured Cordierite Monoliths Washcoated with Wrinkled Silica Nanoparticles

The enzymatic conversion of biomass-derived compounds represents a key step in the biorefinery flowsheet, allowing low-temperature high-efficiency reactions. β-Glucosidases are able to hydrolyze cellobiose into glucose. Wrinkled silica nanoparticles (WSNs) were demonstrated to be a good support for the immobilization of β-glucosidases, showing better performance than free enzymes in batch reaction; on the other hand, immobilized enzyme microreactors (IEMs) are receiving significant attention, because small quantities of reagents can be used, and favorable heat and mass transfer can be achieved with respect to conventional batch systems. In this work, we prepared, characterized, and tested structured enzymatic reactor compounds by a honeycomb monolith, a WSN washcoat, and β-glucosidases as the active phase. Powder and structured materials were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 physisorption, thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FT-IR). Structured catalysts were tested under both batch and continuous flow reaction conditions and compared to powder catalysts (batch reaction). The WSN washcoat was attached well onto the monolith walls, as suggested by the negligible weight loss after ultrasound treatment; the WSNs preserved their shape, porosity, and individual nature when deposited onto the monolith walls. The immobilized enzyme microreactors proved to be very efficient in hydrolysis of cellobiose to glucose, showing a complete conversion under continuous flow reaction at a batch-equivalent contact time equal to 120 min vs. 24 h obtained in the batch experiments. The apparent KM value showed a 20-fold decrease with respect to the batch process, due to the absence of external diffusive transport limitations.

Two-Phase Dibromocyclopropanation of Unsaturated Alcohols Using Flow Chemistry

Dibromocyclopropanations are conventionally done by addition of dibromocarbene to alkenes under phase-transfer conditions in batch reactions using a strong base (50% NaOH (aq)), vigorous stirring and long reaction times. We have shown that cyclopropanation of unsaturated alcohols can be done under ambient conditions using continuous flow chemistry with 40% (w/w) NaOH (aq) as the base. The reactions were generally rapid; the yields were comparable to yields reported in the literature for the conventional batch reaction

Experimental Investigation of Substrate Shock and Environmental Ammonium Concentration on the Stability of Ammonia-Oxidizing Bacteria (AOB)

A wastewater treatment plant (WWTP) frequently encounters fluctuation in ammonium concentration or flow rate (Q), which may affect the stability of ammonium oxidizing bacteria (AOB). In this study, two continuous stirred tank reactors (CSTRs) were operated for 588 days and ammonium concentration was varied at various steady-state conditions. There was no inhibition observed in CSTR operation and AOB acclimated once at a certain ammonium concentration. Cells at an acclimated steady-state concentration (200 mgTAN/L from R(A) and 1000 mgTAN/L from R(B)) were extracted to perform a batch test at operating conditions, and self-inhibition behavior was observed in the batch reaction. In CSTR operation, the environmental ammonium concentration was varied and the specific oxygen uptake rate (SOUR) value was estimated from daily profile data and compared with batch reaction. In the CSTR operation as a substitute for self-inhibition, the SOUR was shifted towards the maximum specific oxygen uptake rate (SOURmax) and no self-inhibition was observed. For further justification of the CSTR’s stability, several total ammonium nitrogen (TAN) concentrations (range from ~−106 to ~+2550 mgTAN/L) were directly added to interrupt the stability of the process. As a substitute for any effect on the SOUR, the CSTRs were recovered back to the original stable steady-state conditions without varying the operational conditions.

Maximizing macromonomer content produced by starved-feed high temperature acrylate/methacrylate semi-batch polymerization

Suitable semi-batch reaction conditions are determined to maximize the fraction of acrylate chains with TDBs while also achieved a target polymer molar mass.