摘要:
The present invention provides a process for the production of cyanamide from urea and/or decomposition products thereof at an elevated temperature with the use of a microporous catalyst, wherein, as catalyst, there is used a zeolite and/or a silicoalumophosphate which is doped with transition metal cations selected from the Group IB and VIIB of the Periodic System. In this way, it is possible to increase the conversion, referred to urea, to 60 to 100%, the selectivity with regard to cyanamide thereby being from about 30 to 50% and with regard to the undesired melamine being .ltoreq.2%.
摘要:
The present invention provides a process for bleaching and delignifying cellulose-containing products with peroxides and/or oxygen and/or ozone, wherein there is additionally used 0.01 to 2.5% by weight of cyanamide and/or cyanamide salts, referred to the dry weight of the cellulose.
摘要:
A curing agent for the production of low gloss powder coatings based on epoxy resins consists essentially of a mixture of the components a) 2-imidazoline derivative having a melting point of >60.degree. C. and b) cyanuric acid as well as, if desired, anticaking agents or/and stabilizers. The low gloss powder coatings produced with these curing agents have the desired low degrees of gloss and good adhesive strengths, they form smooth and uniform surfaces and show no signs of yellowing even after long stoving times.
摘要:
The invention relates to a method for the selective catalytic reduction of nitrogen oxides using ammonia in exhaust gases of vehicles, whereby solutions of guanidine salts with an ammonia forming potential of between 40 and 850 g/kg, optionally in combination with urea and/or ammonia and/or ammonium salts, are catalytically decomposed in the presence of catalytically active, non-oxidation-active coatings of oxides selected from the group containing titanium dioxide, aluminum oxide, silicon dioxide or the mixtures thereof, and hydrothermally stable zeolites which are fully or partially metal-exchanged. The guanidine salts according to the invention enable a reduction of the nitrogen oxides by approximately 90%. Furthermore, said guanidine salts can enable an increase in the ammonia forming potential from 0.2 kg, corresponding to prior art, up to 0.4 kg ammonia per litre of guanidine salt, along with freezing resistance (freezing point below −25° C.). The risk of corrosion of the guanidine salt solutions used according to the invention is also significantly reduced compared to that of solutions containing ammonium formiate.
摘要:
The invention relates to a method for producing N-(phosphonomethyl)glycine involving the following steps: (a) oxidizing N-(phosphonomethyl)iminodiacetic acid (PMIDA) with peroxides or oxygen in an aqueous medium and in the presence of a heterogeneous catalyst at a temperature ranging from 50 to 150° C.; (b) subsequently separating the solid catalyst out of the aqueous reaction suspension of step (a); (c) concentrating the clear reaction solution from step (b), especially by evaporation, and; (d) separating the N-(phosphonomethyl)glycine out of the concentrated reaction solution from step (c), especially by filtration. According to the invention, the aqueous reaction solution from step (d) (mother liquor) is returned with small amounts of N-(phosphonomethyl)glycine and byproducts to step (b) (catalyst separation) and/or to step (c) (concentration). This results in distinctly increasing the yield with a constant product purity and in noticeably reducing the amount of mother liquor.
摘要:
The invention relates to a method for the selective catalytic reduction of nitrogen oxides using ammonia in exhaust gases of vehicles, whereby solutions of guanidine salts with an ammonia forming potential of between 40 and 850 g/kg, optionally in combination with urea and/or ammonia and/or ammonium salts, are catalytically decomposed in the presence of catalytically active, non-oxidation-active coatings of oxides selected from the group containing titanium dioxide, aluminum oxide, silicon dioxide or the mixtures thereof, and hydrothermally stable zeolites which are fully or partially metal-exchanged. The guanidine salts according to the invention enable a reduction of the nitrogen oxides by approximately 90%. Furthermore, said guanidine salts can enable an increase in the ammonia forming potential from 0.2 kg, corresponding to prior art, up to 0.4 kg ammonia per litre of guanidine salt, along with freezing resistance (freezing point below −25° C.). The risk of corrosion of the guanidine salt solutions used according to the invention is also significantly reduced compared to that of solutions containing ammonium formiate.
摘要:
The invention relates to the use of aqueous guanidinium formiate solutions, optionally combined with urea and/or ammonia and/or ammonium salts, for the selective catalytic reduction of nitrogen oxides using ammonia in exhaust gases of vehicles. The inventive guanidinium formiate solutions enable a reduction of the nitrogen oxides by approximately 90%. Furthermore, said guanidinium formiate solutions can enable an increase in the ammonia forming potential from 0.2 kg, corresponding to prior art, up to 0.4 kg ammonia per litre of guanidinium formiate, along with freezing resistance (freezing point below −25° C.). The risk of corrosion of the inventive guanidinium formiate solutions is also significantly reduced compared to that of solutions containing ammonium formiate.
摘要:
The present invention provides an additive for heat-hardenable epoxide resin masses, wherein the additive contains or consists of adducts and/or reaction products of (a) imidazoles of the general formula: ##STR1## in which R.sub.1, R.sub.2, R.sub.3 and R.sub.4, which can be the same or different, are hydrogen atoms, alkyl, alkenyl or alkynyl radicals containing up to 3 carbon atoms or phenyl radicals, said radicals being unsubstituted or substituted, and (b) at least one aromatic hydroxy acid.The additives according to the present invention can be used alone as hardeners or, in combination with other latent hardeners, as accelerators.
摘要:
The invention relates to the use of aqueous guanidinium formiate solutions, optionally combined with urea and/or ammonia and/or ammonium salts, for the selective catalytic reduction of nitrogen oxides using ammonia in exhaust gases of vehicles. The inventive guanidinium formiate solutions enable a reduction of the nitrogen oxides by approximately 90%. Furthermore, said guanidinium formiate solutions can enable an increase in the ammonia forming potential from 0.2 kg, corresponding to prior art, up to 0.4 kg ammonia per liter of guanidinium formiate, along with freezing resistance (freezing point below −25° C.). The risk of corrosion of the inventive guanidinium formiate solutions is also significantly reduced compared to that of solutions containing ammonium formiate.
摘要:
To prepare N-phosphonomethyl glycine,a) aminomethylphosphonic acid or one of its salts in water, if necessary or desirable with the addition of lyes, is reacted with an alkali carbonate and/or alkali hydrogencarbonate or with carbon dioxide and a lye,b) the resulting alkali salt of N-phosphonomethylcarbamic acid is subsequently hydroxymethylated with formaldehyde,c) the salts, resulting from b), of N-hydroxymethyl-N-phosphonomethyl-carbamic acid, if necessary or desirable with addition of a lye, are reacted with hydrocyanic acid and/or a cyanide andd) the N-carboxy-N-phosphonomethylglyconitrile salts thus obtained are treated with acids and converted by means of hydrolysis and decarboxylation into N-phosphonomethyl glycine.In this way, it is possible to obtain excellent yields of high-purity N-phosphonomethyl glycine.