摘要:
Processes and apparatuses are provided for continuously harvesting particles from organic solution-laden near-critical and supercritical fluids. Broadly, the processes and apparatuses utilize a filter or separator comprising a thin membrane supported on a sintered stainless steel tube. A feed stream comprising the desired particles, a supercritical antisolvent for the particles (preferably CO2), and a solvent for the particles, is contacted with the membrane layer of the filter under supercritical conditions for the mixture of antisolvent and solvent. The preferred antisolvents are substantially miscible with the solvent and have a critical temperature of less than 160 DEG C. The desired particles are retained by the filter while the solvent and most of the antisolvent pass through the filter, resulting in separation of the particles from the solvent.
摘要:
Improved isoparaffin-olefin alkylation solid catalyst processes are provided which are characterized by low coke laydown and catalyst deactivation rates and production of valuable branched chain, high octane number alkylates. The processes of the invention involve providing a starting reactant mixture comprising an isoparaffin, an olefin and a co-solvent or diluent (carbon dioxide in molar excess, methane, hydrogen or mixtures thereof), and contacting the reactant mixture with an alkylation catalyst at near-critical or preferably supercritical conditions for the reaction mixture. The carbon dioxide serves as a co-solvent and reduces the critical temperature (Tc) of the reaction mixture, thereby allowing lower reaction temperatures. The isoparaffin and olefin reactants are preferably pretreated to minimize moisture, peroxide and oxygenate impurities therein.
摘要:
Improved oxidation methods are provided wherein a reaction mixture comprising a substrate to be oxidized (e.g., phenols, alkenes) and an oxidation catalyst (typically dispersed in an organic solvent system) is supplemented with a compressed gas which expands the reaction mixture, thus accelerating the oxidation reaction. In preferred practice pressurized subcritical or supercritical carbon dioxide is used as the expanding gas, which is introduced into the reaction mixture together with an oxidizing agent. The inventive methods improve the substrate conversion and product selectivity by increasing the solubility of the oxidizing agent in the reaction mixture.
摘要:
Oxidation process can include: introducing small droplets of liquid reaction mixture having oxidizable reactant, catalyst, and solvent into a reaction zone containing oxygen and diluent gas; and oxidizing the reactant with the oxygen at a suitable reaction temperature and a suitable reaction pressure to produce an oxidized product. The liquid reaction mixture can have an aromatic feedstock having an oxidizable substituent as the oxidizable reactant. The oxidized product can include an aromatic compound having at least one carboxylic acid. For example, the aromatic feedstock can include a benzene ring having at least one oxidizable alkyl substituent, furan hetero-ring having at least one oxidizable alkyl substituent, a naphthalene poly-ring having at least one oxidizable alkyl substituent, derivatives thereof, and mixtures thereof.
摘要:
Allyl alcohol, particularly from biobased sources such as glycerol, is hydroformylated to products including 4-hydroxybutyraldehyde and 4-hydroxy-2-methylpropionaldehyde by forming a homogeneous reaction mixture including allyl alcohol, a rhodium-based hydroformylation catalyst and a near critical liquefiable petroleum gas or mixture of such gases, reacting the near critical liquefiable petroleum gas (or gas mixture)-expanded allyl alcohol substrate with carbon monoxide and with hydrogen in the presence of the catalyst, and recovering substantially all of the petroleum gas or gases overhead by reducing the pressure and degassing the product mixture. Dense propane is especially useful as a single inert solvent/diluent, and substantially no other solvent/diluent is needed.
摘要:
Allyl alcohol, particularly from biobased sources such as glycerol, is hydroformylated to products including 4-hydroxybutyraldehyde and 4-hydroxy-2-methylpropionaldehyde by forming a homogeneous reaction mixture including allyl alcohol, a rhodium-based hydroformylation catalyst and a near critical liquefiable petroleum gas or mixture of such gases, reacting the near critical liquefiable petroleum gas (or gas mixture)-expanded allyl alcohol substrate with carbon monoxide and with hydrogen in the presence of the catalyst, and recovering substantially all of the petroleum gas or gases overhead by reducing the pressure and degassing the product mixture. Dense propane is especially useful as a single inert solvent/diluent, and substantially no other solvent/diluent is needed.
摘要:
Improved method and apparatus (110) for particle precipitation and coating using near- or supercritical fluid conditions. A fluid dispersion (128) having a continuous phase dispersant and at least one precipitable substance therein is contacted with a supercritical fluid (SCF) antisolvent (126) so as to generate focused high frequency antisolvent sonic waves, breaking up the dispersion into extremely small droplets. The enhanced mass transfer rates between the droplets and the antisolvent causes precipitation of very small particles on the order of 0.1-10 microns. In coating processes, a turbulent fluidized flow of core particles is created using SCF antisolvent in an enclosed zone. The core particles are contacted therein at or near supercritical conditions by fluid dispersion containing a dispersant and together with a precipitable substance. The antisolvent depletes the dispersant and the substance is precipitated onto fluidized particles.
摘要:
An improved hydroformylation process is provided, which comprises reacting an olefin with CO and H2 in the presence of a hydroformylation catalyst in a liquid that has been volumetrically expanded with a compressed gas, such as supercritical carbon dioxide.
摘要:
Processes and apparatuses are provided for continuously harvesting particles from organic solution-laden near-critical and supercritical fluids. Broadly, the processes and apparatuses utilize a filter or separator comprising a thin membrane supported on a sintered stainless steel tube. A feed stream comprising the desired particles, a supercritical antisolvent for the particles (preferably CO2), and a solvent for the particles, is contacted with the membrane layer of the filter under supercritical conditions for the mixture of antisolvent and solvent. The preferred antisolvents are substantially miscible with the solvent and have a critical temperature of less than 160 DEG C. The desired particles are retained by the filter while the solvent and most of the antisolvent pass through the filter, resulting in separation of the particles from the solvent.