Recent Patents on Chemical Engineering - Volume 1, Issue 2, 2008

Carbon dioxide is the most abundantly emitted greenhouse gas for which several technologies are being developed and intensively studied for capture and storage, except retrofit of amine scrubbers, none is proven at the commercial scale for treating post-combustion stack gases. Amine scrubbing, membrane separation, wet and dry mineral carbonation, pressure, temperature and electrical swing adsorptions, have been thoroughly reviewed in the 2005 survey by the Intergovernmental Panel on Climate Change (IPCC). However, an innovative approach that has escaped the attention of the recent IPCC concerns using biocatalysts for carbon dioxide hydration to bicarbonate. This review critically evaluates the recent patent literature regarding the different scrubber configurations in use for supporting carbonic anhydrase (CA), an ultrafast zinc-bearing metalloenzyme which catalyzes CO2 hydration to bicarbonate. It describes two membrane contactors using free soluble CA, the first one releasing gaseous CO2 and the second one being used to produce precipitated calcium carbonate (PCC). It also describes two contactors using immobilized CA, namely counter-current and cross-co-current packed columns, and two other contactors using either free or particle-immobilized CA. The review also deals with the use of a cohort of enzymes mimicking metabolic pathways to capture CO2 and potentially produce useful organic compounds.

This review covers synthetic membranes used in the downstream (post fermenter) processing of biotherapeutic proteins manufactured in the biotechnology industry. Biotherapeutics are very expensive proteins, made in gram per liter quantities, in a highly regulated industry. Microfiltration, ultrafiltration, virus removal and adsorption membranes separate and purify the product proteins in the several process steps between the fermenter and the final filled vial. Patent activity for these specialized membranes, primarily in 2006-2007, was reviewed for new membrane development and for novel processes using these membranes.

Before the US. Patent (1949) by Haensel wherein platinum was used as the active metal component in the industrial catalytic reforming catalysts, molybdenum and /or chromium oxides were used but were suffering from very rapid deactivation by coke even when used under high pressures. Platinum containing catalysts enjoyed very high selectivity via producing high yields of high octane C5 + reformates even at relatively much lower pressures. Improvements were then carried out; some concerned with modifying the metal component, and others concerning modifying the support as well as improving the processing schemes. So many patents were disclosing bimetallic or even polymetallic catalysts containing primarily platinum and/or rhenium or iridium, or their combinations, in addition to tin, zinc, germanium, bismuth, phosphorus, or chlorine, etc. These catalysts acquired advantageous activities, selectivities and long time-on stream with maintaining high yields of high octane motor gasoline.

In the present paper, a review of the production methods of activated carbons from various kinds of precursors and their industrial use is presented, based on recently developed patents. The main discussion is divided into two major parts: (i) the activated carbons fabrication industry starting from the choice of the precursor to the activation of the carbonaceous materials and (ii) their diverse applications. Dealing with the activated carbons precursors, recent patents pointed out the beneficial use of several bioresources, agro-industrial wastes, used tires and newspapers for example. In addition, inventors proposed different kinds of fabrication process, with respect to the field in which the activated carbon will be used including wastewater and air treatment, fuel purification and gold recovery. Besides, to enhance the overall economical benefit in using activated carbons, other researchers developed some innovative techniques to regenerate those costly materials, for further utilization of the carbon itself or the recovery of the already sorbed precious compounds. Hence, this review article summarizes recent and important patents relating to the chemical engineering of activated carbons.

Desalination refers to water treatment processes that remove salts from seawater, brackish water or industrial brine solutions. This work reviews potential processes for low cost seawater desalination processes including coprecipitation, capacitive deionization (CDI), forward osmosis (FO) and gas hydrates (GH). Co-precipitation process deals with supersaturating the saline solution, up to 80%, by addition of chemical reagents which results in the precipitation of some of the salts in seawater. The capacitive deionization (CDI) process works on the basis of electrostatic adsorption of ions (e.g. Na+, Cl-, etc.), from the seawater, on a charged pair of high surface carbon electrodes. Carbon electrodes are used due to its conductivity and large surface area that offers a high capacitance and holds electrostatic charge. For high salinity applications, a charge barrier has been added and the process has been given a stage-wise configuration to reduce costing. The forward osmosis (FO) process draws water from the saline feed water by using a highly concentrated draw solution. The draw solution must have high osmotic pressure, contain solutes which are too large to pass through the pores of the membrane and simple and economic to remove and recycle. In gas hydrates desalination, a gas or mixture of gases is brought into contact with the seawater under appropriate conditions of pressure and temperature to form hydrate. The hydrates are then brought to a region of higher temperature and lower pressure, where it dissociates to release fresh water and the hydrate-forming gas. These processes (if scalable) could be cheaper than currently used technologies. The average energy consumption of the capacitive deionization, forward osmosis and gas hydrate processes are 2.5, 1.2 and 27 kWh/m3 which correspond to averages costs of 0.1, 0.6 and 3.5 $/ m3, respectively, which represents a significant reduction in the total desalination cost in the case of CDI and FO processes. The present article deals with new patents in seawater desalination process.

In this paper, virus purification and removal by ultrafiltration are reviewed with specific focus on the patent literature. Membrane ultrafiltration is a pressure driven process which has a wide spectrum of industrial applications but is most attractive for sensitive biological streams carrying molecules like proteins. This process has thus naturally been adopted for the removal of viruses from blood and biopharmaceutical streams as well as for virus removal from drinking water. Safety regulations and associated penalties provide further incentives for limiting virus titers in such bioprocessing. Virus ultrafiltration aims at flux improvement, higher efficiency of removal and elongated filter life. In this regard, the proper choice of membrane material and technique is essential. Recent patents show strives in two directions namely inventions on membrane material design and filtration configuration and operation (methods). The diversity of biological fluids is seen to be a continuous challenge for researchers aiming for generic filtration methods for virus removal.

In the last decade, the supercritical fluid (SCF)-assisted technology generation of micro- or nano- particles of organic, inorganic, or their composite compounds has attracted a growing interest for increasingly sophisticated applications among scientists in various fields. The purpose of this review is to summarize the recent patent literature concerning particle formation techniques using SCFs. Three distinct classes were grouped and surveyed: physical approach, chemical approach, and physico-chemical processes. For the first class, patents are reviewed related to rapid expansion of supercritical solution (RESS), supercritical anti-solvent (SAS), atomization with assistance of SCFs (e.g., particle generation from gas-saturated solutions, carbon dioxide nebulization with a bubble-dryer, and supercriticalassisted atomization), emulsion/suspension-drying process, and impregnation with assistance of SCF. For the second class, patent literature relevant to processes that use SCF as a reactant, i.e. supercritical hydrothermal/solvothermal synthesis, processes that use a SCF as solvent (e.g., thermal decomposition with a supercritical solvent, polymerization in SCFs, and reaction in SCF microemulsion) is summarized. For the third class, patent information concerning reaction- SCF drying and reaction-RESS/SAS is introduced.

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