Catalytic production of petrochemical products from bio-alcohols

Large-scale petrochemicals are typically produced using petroleum olefins as a feedstock. The desire to move toward a sustainable and environmentally friendly chemical industry has lead to interest in the use of bio-derived feedstocks such as alcohols which are currently being produced on an increasingly large scale by fermentation or from synthesis gas. The research investigated the direct catalytic production of ethylene, acetaldehyde, ethylene dichloride (EDC), and ethylene oxide (EO) from ethanol. Two approaches were considered: a) the use of a bi-functional catalyst that combines the dehydration capability with ethylene conversion and b) the use of a double catalytic bed system where ethanol was dehydrated over the 1st bed and the product ethylene was converted over the 2nd bed to yield the desired petrochemical product. The dehydration of ethanol was carried out over several zeolites at different operating temperatures, producing mainly ethylene and diethyl ether. The catalytic selective oxidation of ethanol was tested over silver and/or copper compounds supported on several zeolites. The effects of operating conditions, metal loading, and zeolite acidity were determined. High selectivity to acetaldehyde was achieved. Unfortunately, the direct production of EO from ethanol could not be achieved. The catalytic oxychlorination of ethanol was investigated using CuCl2 as the active compound and zeolites were used as either a support or as a pre-bed. EDC was produced via ethylene oxychlorination as well as the oxychlorination and disproportionation of ethyl chloride. The effects of operating conditions and CuCl2 loading were determined. Higher EDC yield was achieved over the dual-bed system compared to the bi-functional catalyst

Carbon dioxide capture from Flue gases

Global warming and climate change are believed to be caused by the greenhouse effect. CO2 has been regarded as the main contributor to global climate change which directly results in serious environmental problems. Half of the anthropogenic CO2 emission sources are emitted from the combustion of fossil fuels in industries and power plants worldwide. The absorption behavior of Carbon dioxide from flue gases can be studied using conventional absorber and polymeric hollow fiber membrane contractors. An industrial absorber data was compared with simulated data using hollow fiber membrane contractor using the gPROMs software package. In this analysis, with the absorbent solution flowing in the inner side of the fiber bore and the pure gas in the shell, the module was operated in a non-wetted mode. The derived coupled, non-linear partial differential equations were solved by backward finite difference method. The Diethanolamine (DEA) was used as absorbent. The outlet absorbed Carbon dioxide concentration was simulated and studied with respect to the liquid velocity, initial amine concentration and external mass transfer coefficient. The analysis includes the effects of the diameter and length of the fibers on the liquid outlet gas concentration as a function of the liquid velocity in the fiber. It was found that the liquid velocity and initial absorbent concentrations, as well as the fiber inner diameter and length, have a tremendous effect on the Carbon dioxide removal performance

Private sector participation in the water and sanitation sector: alternative options and measurement issues

This paper studies various aspects of the increasing role of private investment in the water services and sanitation (WSS) sector in developing countries. We start by surveying the different types of private sector participation (PSP) in the WSS sector, and the share of public and private responsibilities under each scheme. We then proceed by empirically testing the impact of PSP in the provision of water and sanitation on the average individuals’ welfare with regard to water and sanitation. This paper shows that the private sector has the potential to generate a number of social and environmental benefits for a number of reasons, including its potential to increase efficiency within the sector and increase much-needed levels of investment. Poorer households gain access to affordable services from which they have long been excluded. Furthermore, adverse public health effects of inadequate service provision may be mitigated, and wastewater collection and treatment levels may be increased. The paper also illustrates actual case studies involving PSP in developing countries to present some of the actual improvements that the private sector has already generated, particularly the increased access to water and sanitation, and the rise in water use as suggested by our empirical part.Water demand, public-private partnership, conservation

Polymer Retention during Flow of Polymer Solutions through Porous Media

Polymer solution flow and retention through porous media is of interest to many applications in the oil industry such as drilling, water shut-off and enhanced oil recovery. Operators of mature oil and gas fields are faced with the problem of excessive water production (EWP), which can cause a premature abandonment of some oil and gas wells. It has been found that the injection of high molecular weight polymer solutions through the pay zones of the oil and gas wells would induce a sharp decrease of the water production without affecting the oil and gas production. This effect is called disproportionate permeability reduction (DPR) and the polymer solutions inducing such an effect are called relative permeability modifiers (RPM). Hence, the DPR effect has been utilized in the water shut-off or conformance control of oil and gas wells suffering from EWP. In spite of the extensive research of the DPR effect, there is still a lack of agreement on the mechanisms controlling such an effect and relatively high percentage failures are observed during conformance control field applications. Polymer retention in porous media has been attributed to mechanisms such as bridging-adsorption, adsorption-entanglement, and flow-induced adsorption. These mechanisms have been proposed to account for the increase in flow resistance during or after the flow of polymer solutions through porous media. The DPR effect has been attributed to effects induced by this retained polymer such as steric and lubrication effects, wettability change, segregated oil and water pathways, and swelling and shrinking of the adsorbed polymer layer. The aim of this study is to add knowledge on the effect of polymer solution flow on polymer retention in porous media. In this study, the rheology of high molecular weight polymer solutions was studied using a cone-and-plate setup. Moreover, the characteristics and the effective hydrodynamic thickness of adsorbed polymer layers on glass from these polymer solutions under static conditions were investigated using atomic force microscopy (AFM). Also, quartz crystal microbalance with the dissipation monitoring (QCM-D) was used to investigate the effect of increasing the flow rate of polymer solutions on the adsorbed amount on silica and gold surfaces. Additionally, the mobility reduction and the residual resistance as a result of polymer solution flow through single glass capillaries, 2D and 3D models of porous media were studied. The implementation of the above techniques was used to relate the microscopic effect of the flow of the polymer solutions to the polymer retention in the porous media. The anti-thixotropic behaviour of the polymer solutions, which can be attributed to the shearinduced formation of micron-size transient entanglement networks (TEN), is expected to play a major role in the polymer retention in porous media. These microscopic structures can adsorb on the solid surfaces if the adsorption energy of the polymer/solid system is sufficient. Also, in porous media in which mechanical entrapment is possible, these structures can be entrapped in the small pores and pore throats. Two new mechanisms for polymer retention are proposed in this study: transient-entanglement networks adsorption (TENA) and transient-entanglement networks entrapment (TENE). The TENA is the retention mechanism of the TEN structures in flow systems in which mechanical entrapment is not possible provided that the adsorption energy is sufficient. If mechanical entrapment is possible, then the retention by adsorption and mechanical entrapment are lumped in the TENE mechanism. The results from this study have given a new insight on the flow and retention of polymer solutions through porous media. Hence, it is believed that the improved understanding will improve the design of high molecula

A BIOECONOMIC ANALYSIS OF THE NORWEGIAN SPRING SPAWNING HERRING (NSSH) STOCK

A biological model belonging to the Beverton-Holt age-structured family for the Norwegian spring spawning herring (Clupea harengus) (NSSH) is simulated, the outcome of which compares well with actual data on the fishery. This model is then combined with an economic model to help investigate how optimal a management policy of constant fishing mortality will be for a fishery such as the NSSH, which has a highly fluctuating stock biomass. For the range of constant values of fishing mortality explored, and a simulation time horizon of 20 years, a constant fishing mortality of 0.15 turns out to be economically optimal. It should be noted that this result is sensitive to variations in the assumptions underlying key variables of the fishery. For example, when a constant rather than variable recruitment was assumed, a different optimal fishing mortality rate was obtained.bioeconomic model, herring optimal management, Resource /Energy Economics and Policy, Q57, Q22, Q28,