Wyniki wyszukiwania - BazTech

1

Doświadczalne sprawdzenie chłonności pochłaniaczy wilgoci w różnych warunkach klimatycznych

Korzeniowski Janusz

Problemy Techniki Uzbrojenia

|

2020

|

R. 49, z. 153

87--108

PL

W artykule przedstawiono wyniki badań dostępnych na rynku i aktualnie eksploatowanych pochłaniaczy wilgoci. Doświadczalnie sprawdzono parametry dwóch typów żeli krzemionkowych, glinki bentonitowej i dwóch typów sit molekularnych dostępnych na rynku oraz aktualnie eksploatowanego w sprzęcie uzbrojenia wielokrotnie regenerowanego silikażelu. W ramach pracy określono maksymalną chłonności pochłaniaczy wilgoci dla różnych warunków klimatycznych, minimalny poziom wilgotności względnej (RH) w osuszanej komorze pomiarowej dla różnych ilości absorbentu oraz trwałości wiązania wody w zmiennych warunkach temperaturowych. Analiza otrzymanych wyników pozwoliła porównać rodzaje absorbentów określić ich zalety i wady oraz pozwoliła ocenić stopień zużycia aktualnie eksploatowanego absorbentu wilgoci w sprzęcie uzbrojenia.

EN

The article presents results of tests for moisture absorbers currently used and available on the market. Experimental investigations were carried out for two types of silica gels, the bentonite clay and two types of molecular sieves available on the market, as well as for the reused silica gel currently deployed inweapon systems. As part of the work, the maximum absorbency of moisture absorbers for various climatic conditions, the minimum relative humidity (RH) in the drying measuring chamber for various amounts of absorbent, and the durability of water binding at variable temperature conditions were determined. Analysis of results allowed both to compare advantages and disadvantages of various absorbents, and to assess a degree of the wear for moisture absorbents currently used in armament equipment.

2

Osuszanie gazu syntezowego na sitach molekularnych efektywnym sposobem znaczącego obniżania zużycia energii do produkcji amoniaku

Cwalina Janusz, Bartfai Imre, Csaki Robert

Przemysł Chemiczny

|

2019

|

T. 98, nr 3

409--412

PL

Oceniono energetyczną efektywność osuszania gazu syntezowego na sitach molekularnych, wprowadzonego w ramach modernizacji trzech wytwórni amoniaku zbudowanych w latach 80.-90. XX w. Wbrew rozpowszechnionej opinii dowiedziono, że nawet w przypadku pętli syntezy amoniaku na licencji H. Topsøe osuszanie gazu syntezowego spowodowało obniżenie wskaźnika zużycia energii o 0,3-0,6 GJ/t NH₃. Osuszanie gazu syntezowego w instalacji KBR 1000 t/d połączone z gruntowną rekonstrukcją pętli syntezy amoniaku umożliwiło obniżenie wskaźnika zużycia energii o 0,74 GJ/t NH₃, a z uwzględnieniem korzyści wynikającej z powiększenia zdolności produkcyjnej wytwórni z 1200 do 1400 t/d oszczędność w zużyciu energii przekroczyła 1,15 GJ/t NH₃.

EN

Energy saving as a result of make up gas (MUG) drying on mol. sieves commissioned in 3 NH₃ plants was estd. Even in case of the NH₃ syn-loop licensed by H. Topsøe, significant energy savings resulted from MUG drying amounting to 0.3-0.6 GJ/t NH₃ were achieved. The MUG drying unit implemented in the KBR 1000 tpd NH₃ plant resulted in decrease of energy consumption by 0.74 GJ/t NH₃, and even by 1.15 GJ/t when estd. together with extra benefits from increased capacity of the plant from 1200 to 1400 tpd.

3

Sita molekularne modyfikowane metalami przejściowymi jako katalizatory utleniania węglowodorów

Nowińska K., Held A., Kowalska J.

Wiadomości Chemiczne

|

2009

|

[Z] 63, 3-4

233-268

EN

The development of a one-stage procedure for hydrocarbons oxidation to produce oxygen bearing products is still a challenging task for chemical technology. In the presented paper, the recent achievements in heterogeneous oxidation of benzene to phenol and propene to propylene oxide, as well as an oxidative functionalization of light paraffins have been demonstrated. The successful use of molecular sieves modified with transition metal cations as catalysts for oxidation reactions, performed in the presence of nitrous oxide as an oxidant has been shown. One-stage benzene to phenol hydroxylation was developed and commercialised on the base of iron modified high silica zeolites as catalysts and N_2O as an oxidant. However, structure of the active iron complex and mechanism of the oxidation reaction are still under debate. The most important ideas are presented in the paper. Panov and co-workers [5, 10, 29] underline the role of binuclear iron complex accommodated on ion-exchangeable centres in zeolite channels which easily undergo autoreducion at high temperature and subsequent reoxidation as a result of contact with N2O. Ryder and Bell [35, 36] indicate (FeO_2)+ complex as responsible for benzene hydroxylation, while Hensen and co-workers [37, 38] claim, that not only iron but also aluminium cation is involved in active centre leading to formation of Fe-O-Al complex. Oxidation of light paraffins over N_2O/Fe-ZSM-5 system results in oxydehydrogenation of alkanes and formation of olefins [68, 72, 80]. The possible mechanisms of N_2O decomposition in the presence of alkanes and ODH products, developed in the literature [58, 80-82], are presented. Propylene epoxidation, performed over transition metal cations (iron, vanadium and mixed system) modified molecular sieves, is also presented. Mainly all-silica mesoporous molecular sieves [91, 93, 94] and amorphous silica [7, 95, 96] characterised with very low acidity, show suitable properties as matrices for accomodation of transition metal cations.

4

Nowe metody syntezy pigmentów ultramarynowych z użyciem zeolitów

Jankowska A., Kowalak S.

Wiadomości Chemiczne

|

2008

|

[Z] 62, 7-8

659-682

EN

The natural ultramarine (lazurite, lapis lazuli) has been known and valued since the ancient times as semiprecious gem applied for jewelry, artistic works, decoration and painting. In Middle Ages it was used as excellent, but very expensive pigment. At the beginning of the nineteenth century a method of synthesis of artificial ultramarine has been discovered and it soon became a common inexpensive commercial product applied mostly for production of paints and as an optical brightener. The procedure included heating of the substrate mixtures (kaolin, sulfur, sodium carbonate, reducing agent) in kilns at high temperature (800°C). The technology of ultramarine production has not been substantially changed up to now, whereas the law regulations concerning environment protection imposed in the twentieth century could not accept a serious air pollution (SO2, H2S) always accompanying the production process. Therefore, searching for novel, environmentally friendly procedures becomes challenging. Ultramarine is an aluminosilicate with sodalite structure that contains sulfur anion-radicals (mostly •S3-) combined with Na+ cations embedded inside ?-cages. The sulfur radicals play a role of chromophores (•S3- blue, •S3- yellow). Sodalite is a zeolite and the sodalite units (?-cages) are constituents of structure of several zeolites (LTA, FAU, LTN, EMT). The use of zeolitic structures for encapsulation of sulfur anion radicals appeared very promising. The direct introduction of sulfur radicals from aprotic solutions of oligosulfides [27] was not successful but the thermal treatment of zeolites mixed with sulfur radical precursors (NaSn, S + alkalis) resulted in colored products analogous to ultramarine [24-26, 30, 31]. Zeolites A seem the most useful for preparation of sulfur pigments but other zeolites can be applied as well. The products of various colors (yellow, green blue and sometimes pinky) and shades can be obtained by choosing appropriate zeolite, radi-cal precursor, kind and content of alkaline cation in the initial mixture, temperature (400-800°C) and time of treatment. It was found that zeolite structure can be maintained upon the thermal treatment or it can be transformed (mostly towards SOD) under highly alkaline thermal treatment. The sulfur radicals can also be embedded inside smaller than ?-cages (e.g. CAN) which favors a generation of smaller radicals (i.e. •S2-) [39-42]. It is also possible to incorporate the sulfur compounds into zeolites during their crystallization and then a generation of radical upon heating. The sulfur pigments based on non aluminosilicate matrices (e.g. AlPO4-20) can be also obtained [38, 53]. Generally use of zeolites allows to obtain ultramarine-like pigments with broad range of colors under much milder than conventional conditions and with much lower emission of polluting agents.

5

Oxygen-enriched air for internal combustion engine feeding

Śliwiński K.

Silniki Spalinowe

|

2007

|

R. 46, nr SC2

50-58

EN

The works carried out on combustion engine improvement are focused on increase of their efficiency, effective power, mass decrease, limiting of fuel consumption and reduction of toxicity and quantity of unwanted components of exhaust gases. The aim of these attempts is to satisfy the more and more rigorous regulations concerning environment protection. The basic method of power increase of engines concurrent with improvement of their characteristics lies in increase of a charge dose supplied to the cylinder. There are some ways to achieve this aim. One of this methods lies in increase of the coefficient of filling by growth of air density in the cylinder, another one is application of alternative fuels containing bigger amounts of oxygen compounds. There is still another method of increased oxygen dose as application of nitrogen suboxide N2O. The method up till now not used consists is supply of fuel air mixture enriched in oxygen. This permits to increase the engine power at concurrent decrease in emission of toxic components in exhaust gases. An evident positive of this method is the possibility of its application in automobile vehicles without lowering their traditional properties. Realization of this problem requires application of one of the two technologies of atmospheric oxygen separation. The first of these methods is oxygen separation by use of molecular sieves. This method is known as PSA method (Pressure Swing Adsorption). The other one makes use of oxygen separation from air by mines of membrane processes. There exists also a number of modifications of methods that base on molecular sieves – one of them being the ATF method ( Advanced Technology Fractionator) patented in the USA in 2004. All these methods are used to obtain oxygen applied in industrial processes. Apparatus used for medical purpose as well as the system know as OBOGS (On-Board Oxygen Generating) applied among others in aircraft F-16 for supply of pilot’s oxygen mask are an exception. In connection with the elaborated solution a patent application was made by the chief of the project consisting in adaptation of the ATF method to traction conditions. The carried investigations aim at checking the possibilities of engine power increase limit and influence of this increase on its mechanical and heat resistance and on exhaust gases toxicity. The results of these investigations will influence economical profitability of application of this method in the feeding system of automobile vehicles.

6

Utleniające odwornienie etanu w obecności sit molekularnych

Jagielska E., Mostowicz R., Szarlik S.

Przemysł Chemiczny

|

2007

|

T. 86, nr 4

340-344

7

DeNO(x) na sitach molekularnych zawierających miedź. Cz.2. Katalityczny rozkład NO

Sobczak I., Ziółek M.

Wiadomości Chemiczne

|

2002

|

[Z] 56, 3-4

177-202

EN

Part II of the series dealing with DeNOx carried out on dopper-containing molecular sieves is devoted to the various features responsible for the catalytic activity of Cu-molecular sieves in the NO decomposition. The physico-chemical properties of the catalysts were shown in Part I ("Wiadomości Chemiczne" 2002, 56, 1-2, 83), whereas in Part II they are related to the decomposition of NO. This paper describes the role of the Si/Al and Cu/Al rations, the conditions of the catalysts preparation and activation, the influence of the T-element nature in the framework of molecular sieves as well as co-cations on the yield in the NO decomposition. Moreover, some proposals of the mechanism of this reaction described in the literature are included.

8

DeNO(x) na sitach molekularnych zawierających miedź. Cz.1. Fizykochemiczna charakterystyka katalizatorów

Sobczak Izabela, Ziółek Maria

Wiadomości Chemiczne

|

2002

|

[Z] 56, 1-2

83--111

EN

Since 1986 when Iwamoto and coworkers discovered a very high activity of Cu-ZSM-5 zeolites in NO decomposition a huge number of papers has been devoted to various copper - containing catalysts. This review paper sums up the results presented in so far published articles concerning physico-chemical properties of micro- and mesoporous molecular sieves modified with copper. Cu-ZSM-5 is the most frequently studied zeolite and Cu-AlMCM-41 belongs to the most frequently studied mesoporous materials. Therefore, in this paper a short characteristic of ZSM-5 and MCM-41 molecular sieves is performed, as well as the precise data from FTIR, ESR and H2-TPR studies applied to the characterisation of Cu-state on the catalyst surface are presented (the Cu-species have been identified on the basis of these data).

9

De NO(x) na sitach molekularnych zawierających miedź. Cz.3. Selektywna katalityczna redukcja NO (SKR NO) węglowodorami. Wpływ O(2), H(2)O i SO(2)

Sobczak I., Ziółek M.

Wiadomości Chemiczne

|

2002

|

[Z] 56, 5-6

377-396

EN

Part I of this series exhibited the physico-chemical properties of Cu-containing molecular sieves, whereas, Part II was devoted to the DeNOx carried out via the decomposition of NO. Cu-containing molecular sieves are applied not only in the decomposition of NO but also in the selective catalytic reduction of NO with hydrocarbons (HC-SCR). The latter is the subject of this paper. The selective reduction of NO with hydrocarbons is a new alternative for the removal of NO from the exhausts gases. It is addressed, among others, to the reduction of NO in the presence of a large amount of oxygen. Part III considers also the influence of O2, H2 and SO2 on the activity of Cu-catalysts in both NO reduction with hydrocarbons and NO decomposition.

10

Mezoporowate sita molekularne SiO2-TiO2. Otrzymywanie i właściwości

Kargol M., Mrowiec-Białoń J., Jarzębski A. B., Pająk L.

Inżynieria Chemiczna i Procesowa

|

2001

|

T. 22, z. 3C

669--674

PL

Zastosowano zmodyfikowaną metodę otrzymywania tytanosilikatowych mezoporowatych sit molekularnych typu MCM i HMS. Otrzymano materiały charakteryzujące się powierzchnią właściwą SBET. w zakresie 900-1100 m2/g i objętością porów 1-1,6 cm3/g. Materiały typu MCM oraz z mniejszą zawartością TiO2 cechują się bardziej uporządkowaną strukturą i węższym rozkładem objętości porów.

EN

Titania-silica molecular sieves with specific surface area, SBET in the range of 900-1100 m2/g and pore volume 1-1.6 cm3/g were obtained by a modified method. At low concentration of TiO2 this method gives well ordered structure with a very narrow pore size distribution.

11

Mezoporowate sita molekularne : otrzymywanie i właściwości

Kowalak S., Stawiński K.

Wiadomości Chemiczne

|

2000

|

[Z] 54, 9-10

817-843

EN

The crystalline molecular sieves comprised almost exclusively microporous materials (zeolites and zeolite-like materials). The pore diameter of this materials was mostly in the range 0,3-0,8 nm. Despite a very narrow range of this diameter, which limits the number of molecules to be applied, the crystalline molecular sieves have attained a great commercial importance for many industrial processes (selective adsorption, ion-exchange, catalysis). The attention of many research groups was focused on syntheses of larger pore structures accessible for bulkier molecules. It was not sure, however, whether such structures could be achieved and if so, whether they would be satisfactory stable to be applied for practical purposes. The successful syntheses of crystalline structures of VPI-5, JDF-20, Cloverite, and UTD-1 indicated that extra-large diameters above 1 nm could be obtained. The structures, on the other hand, appeared not very stable and not easy to be synthesized and modified. Therefore, they have not been commercially applied. The important milestone in modem history of the molecular sieves was discovery of novel family of mesoporous, well organized materials in early ninetieths. This new family of the molecular sieves have been presented independently by Mobil and Toyota at the 9th International Zeolite Conference in Montreal. The first examples of the materials consisted exclusively of silica. Soon later the aluminosilicate mesoporous molecular sieves have been presented and then many other chemical compositions have been employed for synthesis of mesoporous molecular sieves. The materials of this kind are generally called M41S. The principle of synthesis of these materials shows some similarity with the preparation of zeolites and zeolite-like materials in respect to employing of the organic compounds as structure directing agents. The role of a template agent plays usually surfactants such as long alkyl chain amines, which form micelles in a solution. The micelle aggregates are then surrounded by inorganic precursors and the well organized array of voids (e.g. tubes) filled with surfactant molecules are formed due to condensation of an inorganic phase. The organic compounds are removed from the pores mostly by means of thermal treatment. A variety of surfactants applied allows to prepare various structures of different pore sizes (2-10 nm). The growing family of mesoporous molecular sieves contains many unique structures. The most common are: the hexagonal unit cell MCM-41, cubic MCM-48, lamellar structure MCM-50, although the number of defined structures is to date many times higher. Contrary to zeolites and other microporous molecular sieves the M41S are not crystalline materials. The XRD indicates usually only one or few reflections at very low range of 2-theta angle. The mesoporous molecular sieves show very high surface areas (usually above 1000 m2/g) and their adsorption/desorption isotherms of type IV often indicate a hysteresis loop. The transmission electron micrographs indicate a pore array in the lattice image. It has been hoped that the novel materials would show a similar catalytic activity as zeolites. These expectations have not been proven satisfactory so far. The catalytic activity of aluminosilicate mesoporous materials resembles rather activity of the amorphous aluminosilicates. The always growing variety of mesoporous structures and of their chemical compositions provides a chance of finding the materials of high and stable catalytic activity. The pore system of this materials is widely studied as a support accommodating the introduced catalytically active compounds. The mesoporous molecular sieves can be used for many other applications such as adsorption (storage of gases), matrices for microelectronic and optical devices, active fillers for polymers etc.

12

Ocena właściwości adsorpcyjnych sit molekularnych po wieloletniej eksploatacji w instalacji oczyszczania wodoru metoda PSA.

Cwalina J.

Prace Naukowe Instytutu Technologii Nieorganicznej i Nawozów Mineralnych Politechniki Wrocławskiej. Konferencje

|

2000

|

Vol. 48, nr 28

172-177

PL

Po 10-letniej pracy instalacji oczyszczania wodoru system PSA wymieniono na nowy pierwotny wsad adsorbentów. Dało to możliwość zbadania sit molekularnych po długoletniej eksploatacji w warunkach przemysłowych.

EN

A first batch of adsorbents of PSA unit has been exchanged for a new one after 10-years of industrial service. It gives an opportunity for examine the adsorption properties of molecular sieves after a long time service in PSA hydrogen purification unit.

13

Mezoporowate sita molekularne - otrzymywanie, właściwości, zastosowanie

Gierczycki A., Jarzębski A.B., Mrowiec-Białoń J., Gierczycka E., Kargol M.

Archiwum Nauki o Materiałach

|

1999

|

T. 20, nr 3

145-153

PL

Przedstawiono zasady preparatyki mezoporowatych sit molekularnych. Omówiono morfologię materiałów i metody jej charakterystyki. Wskazano na szerokie możliwości zastosowania mezoporowatych sit w kształtoselektywnej katalizie, separacji molekularnej oraz w technologiach specjalnych.

EN

The preparation methods for mesoporous molecular sieves have been described. Structural properties and characterization methods were discussed and the prospects of application in the shape selective catalysis, molecular separation and advanced technologies were indicated .