Sulphur reduction catalysts represent a viable option for S reduction in the fluid catalytic cracking (FCC) process. In this paper, a kaolin in situ crystallization catalyst was modified with vanadium and evaluated in a fixed fluid bed (FFB) reactor. The relation between the acidity of the catalyst, the S reduction rate and the catalyst activity is discussed. The results show that increasing weak Lewis acid acidity favours S reduction in the FCC process. Increasing the V content enhances the weak Lewis acidity, so causing the S reduction rate to increase. The kaolin in situ crystallization catalyst modified with 0.6 wt.% of V leads to a 34.5% reduction in the S content of the liquid product. Comprehensive evaluation of the FFB results and the S reduction ability indicates that the catalyst modified with 0.45 wt.% V provided the best performance.

Separation of nitrogen, the major impurity of natural gas, is necessary for quality improvement of the gas. In this study, purified and some ion-exchanged forms of clinoptilolite were used to separate N2 from natural gas. Competitive adsorption of mixtures of N2, CH4 and C2H6 by Cu2+ (Cu-Cp)-, Zn2+ (Zn-Cp)-, Ni2+ (Ni-Cp)- and Mn2+ (Mn-Cp)-exchanged samples was studied at different pressures and ambient temperature. Among the cations studied, Cu2+ has the lowest selectivity towards N2. Samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, BET N2 adsorption and wet chemical analysis techniques.

A series of Cu-substituted goethites, single and co-substituted with Cr, Zn, Cd and/or Pb was prepared, having molar ratios equal to 2.00, 3.33 and 5.00 mol%. All the samples contained only goethite, except Cu-, (Cu,Zn)- and (Cu,Pb)-samples synthesized at 5.00 mol% where hematite was also formed. The presence of Cr/Cd suppressed the hematite-forming effects of Cu. The general sequence of metal entry into the single-metal-substituted goethites was Zn = Cr > Cd > Cu > Pb and in di- (5.00 mol%) and tri- (3.33 mol%) metal-substituted goethites was Cu > Zn > Cd > Cr >> Pb. Cu incorporation increased all the unit-cell parameters in single-metal-substituted goethite, and these parameters increased in combination with other metals as follows: Cd > Zn > Cr > Pb in the multimetal-substituted goethites. The Cu-substituted goethite dissolved faster than pure goethite. Co substitutions of Cr/Pb reduced the dissolution rate (kFe), while substitutions of Cd/Zn increased kFe.

The effects of mechano-chemical treatment on the surface characteristics and sorption properties of hydrotalcite were studied. Non-milled (crushed) and milled samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis and specific area. A milling time of 2 h decreased the particle size of the hydrotalcite samples from 21 to 8.0 nm, the specific area from 97 to 5.7 m2 g–1 and the total pore volume from 0.41 to 0.01 cm3. After the crushed and milled samples had been separately calcined at 500ºC, they were agitated with 10–2 M Na2MoO4 aqueous solutions for 48 h. The molybdate ion content in the regenerated non-milled hydrotalcite samples (HTc-MoO4) was found to be 6.0 meq g–1 while in the milled hydrotalcite (HTm-MoO4) samples this content was 2.5 meq g–1. The lower molybdate content was thought to be a result of compaction and, hence, reduced reactivity of the milled HT samples.

Clay is the main construction material for clay cores of earth-fill dams. Clay minerals swell when they become wet and shrink when they dry out; cracks develop as they lose moisture. If precautions are not taken to prevent seepage through these cracks, dam failures may result. In this study, sand was added to montmorillonite-dominant clay soils to investigate the effect of sand-inclusion rates on the engineering characteristics of clay soils used in the construction of clay cores of earth-fill dams. Changes in the consistency limits, compaction characteristics, permeability, stress-strain relationships and swelling characteristics with increasing sand inclusion rates were evaluated. Based on the results from experimental trials, a 30% sand inclusion rate appears to be the optimum proportion; most of the swelling occurred in the voids of grains and led to permeability levels below the allowable limits for earth-fill dams.

The potassium pools of five major physiographic units of the Urmia region situated in western Azerbaijan province, north-west Iran, were studied to determine the distribution of K forms as functions of clay mineralogy and physiographic units. Soil samples from horizons of ten pedons were selected and analysed for physiochemical properties, clay mineralogy and forms of K. X-ray diffraction patterns revealed that the soils were similar in clay-mineral compositions, consisting of illite, smectite, chlorite, and kaolinite, for the different physiographic units, but vary in the relative amounts of these minerals. The illite content was highest in piedmont plain (P.P) followed by plateau (Pl), river alluvial plain (R.A.P), colluvial alluvial plain (C.A.R) and lowland (L.L) units. Smectite content was highest in Pl followed by P.P, L.L, R.A.P and C.A.P units. Several processes, such as the diversity of weathering rate, biocyclying processes of K accumulation, geomorphologic conditions and soil formation processes, caused significant differences in most K forms in the soils. A wide variation in total K (HF-extractable K) (0.54–1.1%), non-exchangeable K (280–450 mg kg–1) and exchangeable K (217–330 mg kg–1) occurred among the physiographic units, corresponding to variations in their mineralogical compositions, mainly the abundance of illite. Significant differences (P ⩽ 0.05) were found for K, HNO3-extractable K and non-exchangeable K between the soils with large illite contents (30–50%) and with small illite contents (10–30%). A significant positive relationship existed between mineral K and illite content (r2 = 0.85, P ⩽ 0.001) and non-exchangeable K and illite content (r2 = 0.84, P ⩽ 0.001). The results indicated that these pools of K are mainly released from the frayed edges and wedge zones of illite.

There are numerous bentonite deposits, formed by the alteration of volcanic rocks, in the Kapıkaya area (Eskişehir, western Turkey). These deposits can be classified into three groups according to their stratigraphical levels. X-ray diffraction (XRD), scanning electron microscope (SEM), major, rare-earth and trace-element analyses of bentonites and their parent rocks from the Kapıkaya area were used to evaluate the mineralogical and geochemical properties of bentonites and their parental affinities. Mineral assemblages resulting from bentonite deposits consist mostly of clay minerals, gypsum, cristobalite/opal-CT, quartz, feldspar, calcite and dolomite. The clay minerals are represented mainly by dioctahedral smectite and lesser amounts of illite and chlorite. The enrichment and depletion of the elements indicates open-system alteration conditions. The enrichments in MgO, Fe2O3, TiO2, Co, Pb, Zn, and Ni are related to the precipitation of hydrothermal solutions channelled throughout ultramafic sources. The main differences in mineralogy and geochemistry of bentonites from the Kapıkaya area are in the smectite composition and the contents of major, rare-earth and other trace elements. The data obtained show that the types of parent rock the influenced the mineralogical and geochemical compositions of the bentonites.

Mixed-layer illite-smectite samples from the Ordovician and Silurian K-bentonites of the Baltic Basin and the Baltic Shield (Norway, Sweden, Denmark, Poland and Estonia) were dated by K-Ar on several grain fractions and were studied by X-ray diffraction (XRD), both on oriented and random preparations, in order to reveal the conditions of smectite illitization in the area. Authigenic K-feldspar was also dated. The geographic pattern of the degree of illitization (% smectite in illite-smectite measured by XRD) is consistent with other indicators of palaeotemperatures (acritarchs, conodont alteration index, vitrinite reflectance, apatite fission track ages). It reveals the highest maximum palaeotemperatures (up to at least 200ºC) along the Norwegian and the German-Polish branches of the Caledonides and the lowest palaeotemperatures (120ºC) in the central part of the studied area. The distribution of K-Ar ages is not well correlated with this pattern, revealing a zone of older ages (Lower Devonian-Lower Carboniferous) between Denmark and Estonia, and areas of younger ages (Upper Devonian to Carboniferous/Permian boundary) to the north and south of this zone. The zone of older ages is interpreted as the result of illitization induced by a thermal event in front of the Caledonian orogenic belt (migration of hot metamorphic fluids?). The areas of younger ages are considered as representing deep burial illitization under a thick Silurian-Carboniferous sedimentary cover, perhaps augmented by a tectonic load. The K-Ar dates invalidate the hypothesis of a long-lasting low-temperature illitization as the mechanism of formation of the Estonian Palaeozoic illite-smectite. The ammonium content of illite-smectite from the Baltic K-bentonites reflects the proximity of organic-rich source rocks that underwent thermal alteration at the time of illite crystallization.

The CRP-3 drilling project collected sediments from 3 to 939 mbsf (metres below sea floor) in the Victoria Land Basin in Antarctica. The upper sequence (down to ~790 m bsf) is of Cenozoic age and made up of detrital glaciogenic sediments; the characteristics of clay minerals in this part have been reported elsewhere. Here, the compositional features of clay minerals in the lower sequence such as conglomerates, Devonian sandstones and dolerites are described and genetic processes clarified. Clay minerals in the deepest part of the sequence derive from the alteration of different lithologies that mostly make up the sedimentary basin.

Two clay mineral assemblages were characterized through analysis by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). From 790 to 823 mbsf, samples consist of authigenic smectite of variable chemical composition forming imbricated texture of plates or flakes. The smectites probably result from hydrothermal/diagenetic transformation of earlier minerals. The primary smectite cement underwent reorganization during shearing and cataclasis. The lowest part of the sequence (below 823 mbsf) is characterized by an assemblage of kaolinite, mixed-layer illite-smectite, Fe oxyhydroxide, sporadic smectite and poorly crystallized illite. It reflects a stronger alteration process than that recorded in the upper units of core CRP-3, related to hydrothermalism connected with the intrusion of an igneous body. Both assemblages show clear differences in particle morphology, texture and smectite composition to the clay assemblages found in the Cenozoic glaciomarine sediments in the upper sequence. The different phases of alteration appear related to the processes of rifting, exhumation and faulting that characterized this region since the Mesozoic.

Adsorption of cis-2-butene and trans-2-butene on clinoptilolite-rich tuff and ion-exchanged forms was investigated. Clinoptilolite samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, chemical analysis and nitrogen adsorption techniques. Adsorption isotherms for cis and trans 2-butene on purified clinoptilolite (Cp) and modified forms (Na-Cp, K-Cp, Ca-Cp and Mg-Cp) were obtained at pressures up to 2.7 atm. and at 25ºC. The results show that natural clinoptilolite has a considerable potential for separation of the two hydrocarbons. Mg-Cp samples showed maximal uptake of both cis-2-butene and trans-2-butene.

The purpose of this study was to develop a simple and economic method for the preparation of porous bioceramics with controllable macrostructure. Raw materials, including very small organic foam balls as the pore-creating reagent, wax (or paraffin) as the solvent, and oleic acid as the surface active agent, were selected along with bioactive materials such as β-TCP ceramic powder as the main component. The selected components were mixed into a slurry at 30–120ºC and shaped into a green body with a hot die-casting machine at 30–90ºC. The green body was then sintered and porous bioceramics were obtained. The main characteristics of porous bioceramics such as weight loss, compressive strength, connection and size of pores, percolation rate of water, apparent porosity and bulk density were measured. The results indicated that the apparent porosity and the specific surface area were large; the pores were connected in three dimensions and the compressive strength was >1.6 MPa. This study demonstrated that the methods used here are simple and effective in generating porous bioceramics with controllable macrostructures.