The present invention provides crystalline Roxadustat Form-, crystalline Roxadustat Form-, process for the preparation of crystalline Roxadustat Form-, crystalline Roxadustat Form- and its pharmaceutical compositions thereof. The present invention also provides co-crystals of Roxadustat Form RLP, Roxadustat Form RNM and Roxadustat Form RU, process for their preparation and pharmaceutical composition thereof.

The present invention provides crystalline Roxadustat Form-, crystalline Roxadustat Form-, process for the preparation of crystalline Roxadustat Form-, crystalline Roxadustat Form- and its pharmaceutical compositions thereof. The present invention also provides co-crystals of Roxadustat Form RLP, Roxadustat Form RNM and Roxadustat Form RU, process for their preparation and pharmaceutical composition thereof.

Compositions and methods are presented that selectively dissolve calcium from a variety of cementitious materials without dissolving or otherwise degrading calcium silica hydrate (CSH). Preferably, contemplated compositions comprise guanidine bisulfate hydrochloride, which can be prepared from a reaction of urea, hydrochloric acid, and sulfamic acid. Therefore, it is especially contemplated that the compositions contemplated herein are particularly suitable to clean or otherwise condition surfaces of cured concrete, Portland cement-based material, or an aggregate containing CSH.

Compositions and methods are presented that selectively dissolve calcium from a variety of cementitious materials without dissolving or otherwise degrading calcium silica hydrate (CSH). Preferably, contemplated compositions comprise guanidine bisulfate hydrochloride, which can be prepared from a reaction of urea, hydrochloric acid, and sulfamic acid. Therefore, it is especially contemplated that the compositions contemplated herein are particularly suitable to clean or otherwise condition surfaces of cured concrete, Portland cement-based material, or an aggregate containing CSH.

Disclosed is a process for the preparation of a urea product suitable for being diluted with water so as to form an aqueous urea comprising solution for use in a unit for the reduction of NOx in combustion engine exhaust gases, also known as Diesel Exhaust Fluid (DEF) or to be used in De NOx systems of exhaust vapor from industrial furnaces. The process comprises obtaining an aqueous urea solution from or after a recovery section in a urea production process. This solution, which has a low content of impurities, is subjected to flash crystallization at a low pressure, so as to obtain a solid crystallized urea containing product, which is a free-flowing powder containing less than 0.2 wt. % water. This product is packaged under conditions such that the water content in the packaged product is maintained below 0.2 wt. %. The invention can also be used in a method of increasing the capacity of an existing urea plant.

Disclosed is a process for the preparation of a urea product suitable for being diluted with water so as to form an aqueous urea comprising solution for use in a unit for the reduction of NOx in combustion engine exhaust gases, also known as Diesel Exhaust Fluid (DEF) or to be used in De NOx systems of exhaust vapor from industrial furnaces. The process comprises obtaining an aqueous urea solution from or after a recovery section in a urea production process. This solution, which has a low content of impurities, is subjected to flash crystallization at a low pressure, so as to obtain a solid crystallized urea containing product, which is a free-flowing powder containing less than 0.2 wt. % water. This product is packaged under conditions such that the water content in the packaged product is maintained below 0.2 wt. %. The invention can also be used in a method of increasing the capacity of an existing urea plant.

Disclosed is a novel method of controlling the formation of biuret in urea production, and particularly reducing, preventing or reversing such formation. This is accomplished by adding liquid ammonia to a urea aqueous stream. This addition is done at one or more positions downstream of a recovery section in a urea plant. The addition of liquid ammonia serves to shift the equilibrium of biuret formation from urea, to the side of the formation of urea from biuret and ammonia. The invention can be accomplished also in pre-existing urea plant, by the simple measure of providing an appropriate inlet for liquid ammonia, in fluid communication with a source of such liquid ammonia.

Integrated process for the production of urea and urea-ammonium nitrate, comprising: reacting ammonia and carbon dioxide to form a reaction mixture (4) containing urea and unconverted materials, and also comprising the recovery of unconverted materials in a first recovery stage at a first pressure and in a second recovery stage at a second pressure, wherein ammonia-containing offgas (19) released by said second recovery stage are condensed at said second pressure, and said condensed offgas (20) are recycled to said first recovery stage.

Integrated process for the production of urea and urea-ammonium nitrate, comprising: reacting ammonia and carbon dioxide to form a reaction mixture (4) containing urea and unconverted materials, and also comprising the recovery of unconverted materials in a first recovery stage at a first pressure and in a second recovery stage at a second pressure, wherein ammonia-containing offgas (19) released by said second recovery stage are condensed at said second pressure, and said condensed offgas (20) are recycled to said first recovery stage.

An intercalation agent for rapid graphite exfoliation in mass production of high-quality graphene is provided, including a transition metal halide salt, a nitrogen source substance and an organic solvent, and the mass ratio of the transition metal halide salt, the nitrogen source substance and the organic solvent is (1-10):1:(2-10). The transition metal halide salt can form a eutectic with the nitrogen source substance or the organic solvent, and the melting point thereof is lower than that of each component, thereby lowering the reaction temperature, and the preparation cost and difficulty; and a hydrogen bond can also be formed between the nitrogen source substance and the organic solvent, thereby avoiding interlayer stacking of the prepared graphene, thus improving the exfoliation efficiency and the product quality.