Reduction and Analysis of Low Temperature Shift Heterogeneous Catalyst for Water Gas Reaction in Ammonia Production

Radi dobivanja dodatnih količina vodika nakon reakcija parnog reformiranja prirodnog plina te zaštite rada heterogenog katalizatora za sintezu amonijaka bitno je postići i održavati maksimalnu aktivnost, selektivnost i stabilnost heterogenog katalizatora niskotemperaturne pretvorbe (konverzije) vodenog plina. Budući da se heterogeni katalizator isporučuje u oksidiranom obliku, presudno je provođenje pravilnog postupka redukcije. Pravilnim postupkom redukcije i kontinuiranom analizom njegova rada osigurava se nužno potrebna aktivnost, selektivnost i stabilnost tijekom primjene. Da bi se uspješno provela redukcija heterogenog katalizatora za niskotemperaturnu pretvorbu vodenog plina, potrebno je osim procesne opreme za provođenje postupka redukcije primjenjivati pouzdan i realan sustav za mjerenje temperature radi učinkovitog uvida u temperaturne profile unutar reaktora pri provedbi egzotermne reakcije kroz sve slojeve heterogenog katalizatora. Kako bi se provjerila učinkovitost redukcije te omogućila analiza njegova rada, potrebno je u pravilnim razdobljima određivati odnos odgovarajućih temperaturnih profila i konstante ravnoteže reakcije. To se postiže analizom temperaturnih profila u pojedinim slojevima heterogenog katalizatora putem "S" i padajućih temperaturnih krivulja. Na temelju dobivenih podataka može se na zadovoljavajući način određivati optimalna temperatura na ulazu u reaktor kako bi se osigurao maksimalni vijek katalizatora. U radu je opisana redukcija heterogenog katalizatora in situ te dan prikaz sustava za praćenje temperature unutar pojedinih slojeva, kako bi se postigao minimalan sadržaj ugljikova (II) oksida na izlazu iz reaktora. Opisani sustav za praćenje temperature kroz slojeve heterogenog katalizatora osigurao je uspješnu redukciju koja se zasnivala na optimalnom povećanju temperature na ulazu u reaktor. Primijenjenim sustavom postignute su zadovoljavajuće katalitičke značajke (aktivnost, selektivnost i stabilnost). Također je omogućeno predviđanje rada katalizatora te donošenje odluke o potrebi njegove zamjene, što izravno utječe na smanjenje troškova proizvodnje.In order to obtain additional quantities of hydrogen after the reforming reactions of natural gas and protect the ammonia synthesis catalyst, it is crucial to achieve and maintain maximum possible activity, selectivity and stability of the low temperature shift catalyst for conversion of water gas reaction during its lifetime. Whereas the heterogeneous catalyst comes in oxidized form, it is of the utmost importance to conduct the reduction procedure properly. The proper reduction procedure and continuous analysis of its performance would ensure the required activity, selectivity and stability throughout the catalyst’s service time. For the proper reduction procedure of the low temperature shift catalyst, in addition to process equipment, also necessary is a reliable and realistic system for temperature measurements, which will be effective for monitoring the exothermal temperature curves through all catalyst bed layers. For efficiency evaluation of low shift temperature catalyst reduction and its optimization, it is necessary to determine at regular time intervals the temperature approach to equilibrium and temperature profiles of individual layers by means of “S” and “die off” temperature exothermal curves. Based on the obtained data, the optimum inlet temperature could be determined, in order to maximally extend the service life of the heterogeneous catalyst as much as possible, and achieve the optimum equilibrium for conversion of the water gas. This paper presents the methodology for in situ reduction of the low temperature shift heterogeneous catalyst and the developed system for monitoring its individual layers to achieve the minimum possible content of carbon monoxide at the exit of the reactor. The developed system for temperature monitoring through heterogeneous catalyst layers provides the proper procedure for reduction and adjustment of optimum process working conditions for the catalyst by the continuous increase of reactor inlet temperature. The applied system provides maximum catalytic activity, selectivity and stability, as well as enables prediction of the catalyst\u27s performance, which can be the basis for a proper decision on its timely replacement, and significant reduction of production costs

Determination of the phenolic profile of peach (Prunus persica L.) kernels using UHPLC-LTQ OrbiTrap MS/MS technique

Recently, search for new natural sources of compounds with health-enhancing properties prompted interest in fruit kernels. This paper aims to assess peach kernels as a source of nutritionally important compounds, such as phenolic compounds. A total of 25 kernels from various peach germplasm differing in origin and ripening time were characterized by their phenolic profiles. Ultra-high-Performance Liquid Chromatography coupled with Linear Trap Quadrupole and OrbiTrap MS/MS hybrid mass spectrometry was used for determination of 76 different organic compounds. The content of identified phenolic compounds indicated peach kernel as reliable source of bioactive substances with prevalent concentrations of catechin and several phenolic acids. Statistical procedures confirm that phenolic compounds could be used as phytochemical biomarkers to differentiate peach kernel samples belonging to different cultivars/genotypes according to their origin and ripening time. The CATPCA confirmed the possibility of application of chemical profiles presented only as categorical variables for classification