There is provided a urea synthesis method having excellent reliability and productivity with the amount of oxygen used as a corrosion-resistant agent minimized without using special duplex stainless steel. In a urea synthesis apparatus having a synthesis tower, a stripper, and a condenser, general-purpose austenitic-ferritic duplex stainless steel with Cr content: 21 to 26 wt %, Ni content: 4.5 to 7.5 wt %, Mo content: 2.5 to 3.5 wt %, N content: 0.08 to 0.30 wt %, C content: 0.03 wt % or less, Si content: 1.0 wt % or less, Mn content: 2.0 wt % or less, P content: 0.04 wt % or less, and S content: 0.03 wt % is used as a urea synthesis apparatus material in at least some of parts where the urea synthesis apparatus comes into contact with a fluid having corrosiveness, and oxygen feed concentration with respect to carbon dioxide is 100 to 2,000 ppm.

Methods for making acrylic acid, acrylic acid derivatives, or mixtures thereof by contacting a stream containing hydroxypropionic acid, hydroxypropionic acid derivatives, or mixtures thereof with either an active catalyst containing an amorphous and partially-dehydrated phosphate salt or a precursor catalyst containing a crystalline phosphate salt in a reactor with a low corrosion rate are provided.

The invention relates to the use of a reactor, methods, and devices for the quantitative recovery of molecular hydrogen from solid, liquid, or gaseous substances which contain hydrogen and which have heteroatoms, as well as to reactors. In this case, the reactors have material containing chromium. The subject matter of the invention also includes the use of the reactor, the method, and the device for the compound-specific or component-specific measurement of the isotope ratio (.sup.2H) of hydrogen using online apparatuses.

A process for producing an anti-erosion coating on an inner or outer metal wall of a chamber of a fluid catalytic cracking unit, comprising: (i) the shaping of a honeycomb metal anchoring structure, said anchoring structure being formed from a plurality of strips connected in pairs by joining assembly portions of these strips so as to form a plurality of cells between two adjacent strips, (ii) the fastening of said anchoring structure by welding to said metal wall, so that each cell of the anchoring structure is welded to the wall of the chamber at least at the junctions between the contiguous assembly portions of two adjacent strips, and (iii) the insertion of a composite material into the cells from the metal wall and at least up to the upper longitudinal edge of each strip.

Disclosed is a hydrothermal synthesis device for continuously preparing an inorganic slurry using a hydrothermal method. The hydrothermal synthesis device includes a mixer to mix at least one precursor solution for preparing an inorganic material, injected via at least one supply tube, to prepare an intermediate slurry, a connection tube provided at a side of the mixer, continuously discharging the prepared intermediate slurry to a reactor, and having an inner surface contacting a precursor solution mixture on which abrasive polishing has been performed, and the reactor performing hydrothermal reaction of the intermediate slurry supplied from the connection tube by receiving a liquid stream heated to supercritical or subcritical conditions using a heat exchanger and connected to the connection tube into which the intermediate slurry prepared from the mixer is introduced and to at least one injection tube into which the heated liquid stream is injected.

An anti-coking surface having a thickness up to 15 microns comprising from 15 to 50 wt. % of MnCr.sub.2O.sub.4 (for example manganochromite); from 15 to 25 wt. % of Cr.sub.0.23Mn.sub.0.08Ni.sub.0.69 (for example chromium manganese nickel); from 10 to 30 wt. % of Cr.sub.1.3Fe.sub.0.7O.sub.3 (for example chromium iron oxide); from 12 to 20 wt. % of Cr.sub.2O.sub.3 (for example eskolaite); from 4 to 20 wt. % of CuFe.sub.5O.sub.8 (for example copper iron oxide); and less than 5 wt. % of one or more compounds chosen from FeO(OH), CrO(OH), CrMn, Si and SiO.sub.2 (either as silicon oxide or quartz) and less than 0.5 wt. % of aluminum in any form provided that the sum of the components is 100 wt. % is provided on steel.

Apparatus and methods are provided for converting methane in a feed stream to acetylene. A hydrocarbon stream is introduced into a supersonic reactor and pyrolyzed to convert at least a portion of the methane to acetylene. The reactor effluent stream may be treated to convert acetylene to another hydrocarbon process.

Apparatus and methods are provided for converting methane in a feed stream to acetylene. A hydrocarbon stream is introduced into a supersonic reactor and pyrolyzed to convert at least a portion of the methane to acetylene. The reactor effluent stream may be treated to convert acetylene to another hydrocarbon process.

Apparatus and methods are provided for converting methane in a feed stream to acetylene. A hydrocarbon stream is introduced into a supersonic reactor and pyrolyzed to convert at least a portion of the methane to acetylene. The reactor effluent stream may be treated to convert acetylene to another hydrocarbon process.

Methods for converting carbon dioxide (CO.sub.2) into graphene are described. The methods include contacting a metal with gaseous carbon dioxide, and irradiating a surface of the metal with at least one laser beam to convert the gaseous carbon dioxide into graphene on the surface of the metal. Systems for converting carbon dioxide into graphene are also described.