Zealand Coals Research Articles

The retention of precursor biotic signatures in the organonitrogen and organooxygen compounds of immature fine-grained sedimentary rocks

To reveal the impact of biomass input (marine algae, terrestrial plants and lacustrine Botryococcus braunii) on the composition of high molecular weight organooxygen and organonitrogen compounds (Ox, Ny and NyOx), solvent extracts of immature–early mature rock and coal samples were systematically characterized by Fourier transform ion cyclotron resonance mass spectrometry using different ionization modes. In total, 16 samples from the marine Schöneck, Dynow and Posidonia formations, the lacustrine Wealden Formation and the terrestrial New Zealand coals were investigated.Coals as the in-situ deposits of terrestrial plants consist to a great degree of aromatic polyoxygenated Ox and N1Ox compounds, representing the degradation products of lignin like phenolic ketones and carboxylic acids as well as their condensation products with the degradation intermediates of labile organonitrogen compounds. Aliphatic Ox moieties derived from plant protective constituents principally waxes and cutan show a pronounced even or odd carbon number predominance of the C23–C33 species with C26, 28, 30 or C27, 29, 31 as the major homologs. In contrast, marine and lacustrine microbial communities contribute plentiful middle-chain C22, C24 or C23, C25 Ox compounds. Marine rock extracts are characterized by abundant organonitrogen compounds, especially N2 and N2Ox classes, interpreted as signatures of protein-rich marine algae that were successfully preserved via a degradation-recondensation pathway, whereas the low protein content of lacustrine Botryococcus braunii is reflected by a low amount of N1Ox and N1 classes. Highly aliphatic algaenan of Botryococcus braunii sterically protected its oxygen-bearing groups from degradation, leading to a great abundance of Ox compounds, furthermore, it characterizes the Botryococcus braunii source by substantial heteroatomic species containing more than 40 carbon atoms.

Snail assemblages: interrogating an environmental controversy involvingPowelliphanta augustaand the mining industry inAotearoaNewZealand

AbstractIn 2004, a controversy arose in Aotearoa New Zealand's coal mining sector that involvedPowelliphanta augusta, a species of land snail. This paper considers that controversy in terms of emergent assemblages involving the snail, the mining industry, the Department of Conservation, political action by environmental non‐government organisations, and public expressions of environmental and other values. Three sets of relations embedded in those assemblages are examined—those related to positioning and organising nature; values, politics, and power relations; and human and non‐human materialities. Those relations illuminate how a protracted controversy and its objects form a “social test bed” for contested views in legislation and guidelines dealing with economy, conservation, and restoration. To assess the dynamics, complexities, and contingencies of such relations, attention is paid to the controversy's detailed time line and legal framing, as well as to ontological shifts of snail and habitat and snail metrics. This analytical focus highlights the shifting quality of ideas about how the snail and its habitat are understood as entangled in fraught and mutating strategies of translocation that are played out in a particular regulatory setting. It also provides insights into international geographical efforts to re‐shape environmental governance and management.

Manganese and trace element removal from New Zealand coal mine drainage using limestone leaching beds

ABSTRACTLimestone leaching beds are used in passive treatment systems to remove Mn(II) from mine drainage. Removal typically involves a combination of biotic and abiotic mechanisms. Six laboratory scale reactors were set up to examine the relative importance of different removal mechanisms of Mn. Duplicate reactors contained limestone, limestone with pyrolusite, and quartz. Acid mine drainage (AMD) containing 2 mg/l Mn, 0.3 mg/l Zn, and 0.08 mg/l Ni was fed in two streams to the duplicate sets of reactors, one stream was treated with biocide. Removal of Mn by limestone alone is minimal, and is enhanced by the presence of pyrolusite in a reactor. The most effective removal of Mn was achieved in the biotic limestone reactors, and microbial Mn (II) oxidation appears to be important for optimal removal of Mn from solution. Ni and Zn removal appeared coupled to Mn removal, likely due to their sorption onto Mn oxide surfaces.

Molecular characterization of extracted dissolved organic matter from New Zealand coals identified by ultrahigh resolution mass spectrometry

Knowing the composition, molecular size and structure of water-soluble organic compounds are the prerequisites for a better understanding of water-rock interactions and of the main controls on their release from natural organic matter in shale environments and coal seams over both geological and human timescales. In this study, extracted dissolved organic matter (DOM) from two lignites and three bituminous coals of New Zealand was analyzed by high resolution Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) combined with electrospray ionization (ESI) in negative ion mode after solid phase extraction (SPE). Compared to DOM in natural waters, the yields of extracted DOM of New Zealand coals were 10 to 100 times higher while the compounds showed an elevated aromaticity as indicated by lower H/C ratios. Elevated abundances of benzenepolycarboxylic acids (BPCAs) and naphthalenepolycarboxylic acids (NPCAs) with different numbers of carboxyl and hydroxyl groups in the FT mass spectra of all five samples have been confirmed by GC-MS. Oxygen containing compounds are the dominant elemental class in the extracted DOM of bituminous coals and lignites. However, the relative intensity distributions of individual oxygen classes as well as of the double bond equivalents (DBE) in the extracted DOM of the bituminous coals differ from those in the lignites. The low abundance of O9–16 in the bituminous coals might reflect the loss of oxygen via eliminations of carboxyl and carbonyl groups with increasing maturation. Furthermore, the extracted DOM of bituminous coals contains higher percentages of aromatic and condensed aromatic compounds than the extracted DOM of the lignites. A modified aromaticity index (AIcoal) was established to evaluate aromaticity of the extracted DOM based on sample-specific calculated fraction of oxygen numbers bound in π-bonds instead of an assumed average of 50%.

Improving spatial predictability of petroleum resources within the Central Tertiary Basin, Spitsbergen: A geochemical and petrographic study of coals from the eastern and western coalfields

Central Tertiary Basin (CTB) coals from a variety of palaeogeographic conditions within the Longyear and Verkhnij seams, were sampled to assess the relationship between the petroleum present, the remaining generation potential and coal geochemistry in order to improve the spatial predictability of petroleum resources within the basin. Vitrinite reflectance (VR) values from the CTB coals have been shown to be suppressed (Marshall et al., 2015b). This study attempts to quantify and correct for this suppression effect by applying the Lo (1993) method (LoVR), which uses Hydrogen Index (HI) values to modify VR data, and the coal Rank(Sr) scale of Suggate (2000, 2002), a technique not affected by suppression. In addition, the oil generation and expulsion thresholds for the CTB coals were investigated, with discussions on oil potential versus marine influence upon the mires in which the coals formed.A pseudo-van Krevelen diagram shows that the majority of the coals plot on the Type II kerogen line, while the remainder plot between the Types II and III kerogen lines, with HI between 151 and 410mgHC/g TOC; however, maceral analysis shows that Type III kerogen predominates. This is attributed to the presence of abundant fluorescing (oil-prone) vitrinites. The LoVR, Tmax and Rank(Sr) parameters all show that maturity increases from basin margins towards basin centre (i.e. from Bassen to Lunckefjellet, to Breinosa and Colesdalen) and indicate that all the coals are within the oil generation window. The marginal samples at Bassen are within the early mature stage of the oil window (i.e. ~0.7% RO); meaning the threshold for oil generation in the basin could not be clearly defined. However, the observed maturation trend somewhat parallels the maturation pathway of the New Zealand Coal Band (NZ Coal Band) and the “envelope” of the Sykes and Snowdon (2002) NZ coal data-set; therefore, it is considered that the oil generation threshold for the CTB coals is likely at Rank(Sr) ~9–10, Tmax~420–430°C in line with the observed rise in Bitumen Index (BI). Some of the Lunckefjellet coals and all the Breinosa and Colesdalen coals have either reached or progressed beyond the threshold for oil expulsion as indicated by the peak in HI at Rank(Sr) ~11–12, LoVR ~0.75–0.85% RO, Tmax~430–440°C. The peak in BI at Rank(Sr) ~12.5–13.5 suggests that some of the Lunckefjellet and Breinosa coals, and all the Colesdalen coals have reached the “effective oil window”.Total sulphur (ST) contents range between 0.46 and 12.05% indicating non-marine to strong marine influence upon precursor peats, with ST contents of the Longyear seam appearing to record instances of coastal retreat associated with base level rise. Marine deposition seems to significantly control the distribution of oil-prone coals within seams and across the CTB. The levels of marine influence (as indicated by ST content) show clear positive relationships between BI and HI within the Bassen samples because they have not started expelling oil. Conversely, the levels of marine influence show clear negative relationships with BI and HI within the Colesdalen samples because they have commenced oil expulsion, and probably reached the “effective oil window”. The more marine influenced coals appear to have commenced petroleum generation relatively earlier, which is a plausible explanation why the coals from the Lunckefjellet locality appear to be at different stages within the oil window.

Differences in bitumen and kerogen-bound fatty acid fractions during diagenesis and early catagenesis in a maturity series of New Zealand coals

Oxygen-bearing functional groups, in particular the carboxylic groups of acids and esters, are mainly responsible for the chemical reactivity of sedimentary organic matter. We have studied kerogen and bitumen fractions from a coalification series from the New Zealand Coal Band covering the rank range from 0.28% to 0.80% vitrinite reflectance. We investigated the composition of fatty acids separated from the bitumen, and compared this to the distribution of kerogen-bound fatty acids (esters) obtained after selective chemical degradation of the macromolecular organic matter. We found remarkable differences in the fatty acid composition between bitumen and kerogen-bound acids, both in the short (<C20) and long chain (≥C20) fatty acid range. The compositions of these two acid fractions changed independently as a function of maturation. This points to the long and short chain fatty acids in bitumen and kerogen having different susceptibilities towards degradation, possibly as a result of their different solubilities in the pore water. The compositional differences may further reflect the occurrence of different types of bitumen e.g. if bitumen is trapped in organic micropores of the macromolecular network. Application of the carbon preference index for fatty acids (CPIFA) of bitumen and kerogen-bound acids revealed a linear correlation to the Tmax maturity parameter. This shows that the CPIFA has a clear relation to thermal stability and, thus, reactivity of the buried organic matter. The difference in slopes of CPIFA vs. Tmax for short and long chain as well as bitumen and kerogen-bound acids may indicate their different degradation susceptibilities. The short chain fatty acids of the bitumen show the highest susceptibility whereas the kerogen-bound long chain fatty acids seem to be most resistant towards diagenetic degradation.

The structural evolution of organic matter during maturation of coals and its impact on petroleum potential and feedstock for the deep biosphere

The structural evolution of coals during coalification from peat to the end of the high volatile bituminous coal rank (VRr=0.22–0.81%) has been studied using a natural maturity series from New Zealand. Samples were studied using a range of standard coal analyses, Rock–Eval analysis, infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and pyrolysis gas chromatography (Py-GC). The structural evolution of coal during diagenesis and moderate catagenesis is dominated by defunctionalisation reactions leading to the release of significant amounts of oxygen and thereby to an enrichment of aromatic as well as aliphatic structures within the residual organic matter. Based on the evolution of pyrolysis yields and elemental compositions with maturity it can be demonstrated that oxygen loss is the major cause for increasing Hydrogen Index values or hydrocarbon generating potentials of coals at such maturity levels. For the first time, the loss of oxygen in form of CO2 has been quantified. During maturation from peat to high volatile bituminous coal ranks ∼10–105mg CO2/g TOC has been released. This is equivalent to 2.50E−4 to 1.25E−3mg CO2 generated from every litre of sediment per year falling into the range of deep biosphere utilisation rates. Immature coals, here New Zealand coals, therefore manifest the potential to feed deep terrestrial microbial life, in contrast to more mature coals (VRr>∼0.81%) for which defunctionalisation processes become less important.

Pore size distribution and accessible pore size distribution in bituminous coals

The porosity and pore size distribution of coals determine many of their properties, from gas release to their behavior on carbonization, and yet most methods of determining pore size distribution can only examine a restricted size range. Even then, only accessible pores can be investigated with these methods. Small-angle neutron scattering (SANS) and ultra small-angle neutron scattering (USANS) are increasingly used to characterize the size distribution of all of the pores non-destructively. Here we have used USANS/SANS to examine 24 well-characterized bituminous and subbituminous coals: three from the eastern US, two from Poland, one from New Zealand and the rest from the Sydney and Bowen Basins in Eastern Australia, and determined the relationships of the scattering intensity corresponding to different pore sizes with other coal properties. The range of pore radii examinable with these techniques is 2.5 nm to 7 μm. We confirm that there is a wide range of pore sizes in coal. The pore size distribution was found to be strongly affected by both rank and type (expressed as either hydrogen or vitrinite content) in the size range 250 nm to 7 μm and 5 to 10 nm, but weakly in intermediate regions. The results suggest that different mechanisms control coal porosity on different scales. Contrast-matching USANS and SANS were also used to determine the size distribution of the fraction of the pores in these coals that are inaccessible to deuterated methane, CD 4 , at ambient temperature. In some coals most of the small (~ 10 nm) pores were found to be inaccessible to CD 4 on the time scale of the measurement (~ 30 min–16 h). This inaccessibility suggests that in these coals a considerable fraction of inherent methane may be trapped for extended periods of time, thus reducing the effectiveness of methane release from (or sorption by) these coals. Although the number of small pores was less in higher rank coals, the fraction of total pores that was inaccessible was not rank dependent. In the Australian coals, at the 10 nm to 50 nm size scales the pores in inertinites appeared to be completely accessible to CD 4 , whereas the pores in the vitrinite were about 75% inaccessible. Unlike the results for total porosity that showed no regional effects on relationships between porosity and coal properties, clear regional differences in the relationships between fraction of closed porosity and coal properties were found. The 10 to 50 nm-sized pores of inertinites of the US and Polish coals examined appeared less accessible to methane than those of the inertinites of Australian coals. This difference in pore accessibility in inertinites may explain why empirical relationships between fluidity and coking properties developed using Carboniferous coals do not apply to Australian coals. Fraction of 8 nm radius pores in coals inaccessible to methane versus maceral composition. X, European and American coals; diamonds, Australian and New Zealand coals. ► The fraction of fine pores in coals decreases with increasing rank. ► The fraction of fine closed pores in bituminous coals is not affected by rank. ► Inertinite in Australian coals has less closed pores than that in Laurasian coals.

Structural insights from boron tribromide ether cleavage into lignites and low maturity coals from the New Zealand Coal Band

Ether functionalities form an important cross-linking structure within the macromolecular organic matrix of lignites and coals. To obtain a deeper insight into the complex internal structure of such macromolecules and the maturation related changes of the ether compounds within the network structure, boron tribromide (BBr 3) ether cleavage was applied to a series of lignite and coal samples of different maturity ( R 0 0.27–0.80%) obtained from coal mines and natural outcrops from the North and South Island of New Zealand. Terminal ether-bound alcohols rapidly decrease during diagenesis and occur only in low amounts during the catagenetic stage. Comparison between ester- and ether-bound terminal alcohols indicates a parallel decreasing trend during the diagenetic stage, suggesting that the stability differences between both linkages are not large enough to be observed in maturation processes over geological time scales. Polyether compounds were detected with chain length up to five carbon atoms. After a small decrease during the diagenetic phase these compounds occur in relatively high concentrations, even in the main catagenetic stage. This suggests that these linkage structures represent important cross-linking substructures within the macromolecular matrix of lignites and coals being sterically protected within the macromolecular network during the maturation process. Additional cross-linking substructures were (poly)ether aromatics, esters and ketones.

Correlation of acid base accounting characteristics with the Geology of commonly mined coal measures, West Coast and Southland, New Zealand

Assessment of the potential for waste rock at coal mine sites to produce acid mine drainage is an important part of mine planning and operations and is commonly assessed using acid base accounting analyses. The underlying factor that controls mine drainage chemistry is the mineralogical composition of the coal measures sequences which in turn is controlled by several geological factors including provenance, depositional environment, diagenetic processes and tectonic setting. Therefore, coal mine drainage chemistry is directly linked to the geology of coal measures sequences. Our research uses acid base accounting data to identify relationships between coal measures geology and acid production potential for Brunner, Paparoa and Morley Coal Measures as well as Gore Lignite Measures. Our data is from several sources and reflects areas in these sets of coal measures where mining or exploration is underway. In general Brunner Coal Measures are strongly acid producing especially fine grained rocks and this relates to a coastal depositional environment, common diagenetic pyrite, overlying transgressive marine rocks and compositional maturity. Morley and Paparoa Coal Measures are mostly non-acid forming relating to fluvial - lucustrine depositional environments, overlying coal measures, diagenetic carbonates, and possibly carbonates from source rocks. Gore Lignite Measures are mostly non-acid forming, however, some acid forming rocks are present. Gore Lignite Measures are delta plane deposits with occasional marine influence. Datasets from Brunner, Paparoa and Morley Coal Measures as well as Gore Lignite Measures also demonstrate some of the limitations of acid base accounting analyses. For example, oxidation steps in acid base accounting analyses designed to dissolve pyrite also react with organic material and this causes a false positive analysis. Other assumptions common in acid base accounting such as use of total S content to calculate pyrite related acidity are inappropriate for some samples because of other forms of S in these samples. Despite the interferences, standard acid base accounting tests and procedures are very useful for first pass predictions of mine drainage chemistry and datasets from commonly mined New Zealand coal measures can be successfully related to geological processes.

Maturation related changes in the distribution of ester bound fatty acids and alcohols in a coal series from the New Zealand Coal Band covering diagenetic to catagenetic coalification levels

A rank series of lignites and coals of low to moderate maturation levels (vitrinite reflectance (R0): 0.27–0.8%) from the New Zealand Coal Band were investigated using alkaline ester cleavage experiments to reveal compositional changes of ester bound components (fatty acids and alcohols) during increasing maturation. Ester bound alcohols are found to be present in highest amounts in the very immature lignite samples (R0: 0.27–0.29%), but show a rapid decrease during early diagenesis. Ester bound fatty acids also show an initial exponential decrease during diagenesis, but reveal an intermittent increase during early catagenesis before decreasing again during main catagenesis. This intermittent increase was related to the short chain fatty acids. To obtain a maturity related signal and to eliminate facies related scattering in the amounts of fatty acids in the coal samples, the carbon preference index of fatty acids (CPIFA) parameter is introduced here. For the long chain fatty acids (C20–C32) originating from terrigenous plant debris, the CPIFA decreases with increasing maturity, showing a strong maturation related signal. During diagenesis, the same trend can be observed for the short chain fatty acids, but the intermittent increase in the amounts of short chain fatty acids is also accompanied by high CPIFA values. This indicates less altered organic biomass at this advanced maturation level and is in contrast to the mature CPIFA signal of the long chain fatty acids of the same samples. One possible reason for this discrepancy could be extremely different amounts of short and long chain fatty acids in the original source organic matter of these samples. However, another intriguing explanation could be the incorporation of immature bacterial biomass from deep microbial communities containing C16 and C18 fatty acids as main cell membrane components. Deep microbial life might be stimulated at this interval by the increasing release of thermally generated potential substrates from the organic matrix during early catagenesis. In contrast to the fatty acids, the high amounts of alcohols in the immature lignite samples are also visible in the alkene distribution from the open system pyrolysis experiments of the organic matrix before and after saponification.

Changes in bulk properties and molecular compositions within New Zealand Coal Band solvent extracts from early diagenetic to catagenetic maturity levels

The bulk properties and bitumen molecular compositions of a rank-series of 38humic coals from the New Zealand Coal Band (Cretaceous–Cenozoic) have been analysed to investigate early maturation processes affecting coaly organic matter through diagenesis to moderate catagenesis (Rank(Sr) 0.0–11.8, Ro 0.23–0.81%). The samples comprise a relatively restricted range of vitrinite rich coal types formed largely from higher land plant material under relatively oxic conditions, but with a significant contribution from microbial biomass. With increasing rank, total organic carbon contents show a general increase, whereas moisture and asphaltene contents decrease. Bitumen yields also decrease through the stages of diagenesis and early catagenesis (Rank(Sr)<9, Ro<0.55%), indicating partial loss of initial bitumen during early maturation. Thermal generation of hydrocarbons begins slowly at Rank(Sr)∼5–6 (Ro∼0.40%) as indicated by the constant occurrence and gradual increase of isoprenoids (e.g., pristane and phytane) and hopanoids in their more mature αβ configuration. This early phase of catagenesis, not previously recognised in New Zealand coals, is followed at Rank(Sr)∼9 (Ro∼0.55%) by the main catagenesis phase characterised by a more rapid increase in the generation of hydrocarbons, including total n-alkanes, isoprenoids and αβ-hopanes. Changes in the maturity of New Zealand coals can be traced by the Carbon Preference Index and several hopane maturity parameters, including 22S/(22S+22R), αβ/(αβ+βα) and ββ/(αβ+βα+ββ).

Influence of in-situ bitumen on the generation of gas and oil in New Zealand coals

New Zealand coals of peat to high volatile bituminous rank have been studied in order to assess the effect of in-situ bitumen (soluble in a methanol:acetone:chloroform azeotrope), on petroleum potential during progressive maturation. Both non-extracted and extracted coals, as well as the extracted bitumen itself, were analyzed using Rock-Eval and pyrolysis gas chromatography. The difference in yields between non-extracted and extracted coals, attributable to the influence of bitumen, were compared with direct measurements made on the bitumen itself. Major compositional changes in pyrolysis products were seen when the bitumen was finely dispersed throughout the kerogen matrix. Notably, second-order reactions between kerogen and bitumen during pyrolysis reduce primary gas yield and enhance both oil yield and potential secondary gas yield. The stabilization of free radicals, and prevention of recombination/repolymerization processes have been attributed to the presence of the dispersed in-situ bitumen. These results demonstrate that petroleum formation in coals likely proceeds via intermolecular interactions and not simply first order cracking. The common procedure of employing solvent extraction prior to pyrolysis is clearly not appropriate when assessing the petroleum potential of coal.

Gasification of New Zealand Coals: A Comparative Simulation Study

The aim of this study was to conduct a preliminary feasibility assessment of gasification of New Zealand (NZ) lignite and sub-bituminous coals, using a commercial simulation tool. Gasification of these coals was simulated in an integrated gasification combined cycle (IGCC) application and associated preliminary economics compared. A simple method of coal characterization was developed for simulation purposes. The carbon, hydrogen, and oxygen content of the coal was represented by a three component vapor solid system of carbon, methane, and water, the composition of which was derived from proximate analysis data on fixed carbon and volatile matter, and the gross calorific value, both on a dry, ash free basis. The gasification process was modeled using Gibb's free energy minimization. Data from the U.S. Department of Energy's Shell Gasifier base cases using Illinios No. 6 coal was used to verify both the gasifier and the IGCC flowsheet models. The H:C and O:C ratios of the NZ coals were adjusted until the simulated gasifier output composition and temperature matched the values with the base case. The IGCC power output and other key operating variables such as gas turbine inlet and exhaust temperatures were kept constant for study of comparative economics. The results indicatedmore » that 16% more lignite than sub-bituminous coal was required. This translated into the requirement of a larger gasifier and air separation unit, but smaller gas and steam turbines were required. The gasifier was the largest sole contributor (30%) to the estimated capital cost of the IGCC plant. The overall cost differential associated with the processing of lignite versus processing sub-bituminous coal was estimated to be of the order of NZ $0.8/tonne. 13 refs., 9 tabs.« less

Pyrolytic assessment of oil generation and expulsion from a suite of vitrinite-rich New Zealand coals

Pyrolysis–gas chromatography (PY–GC) of Tara-1 coals (Great South Basin, New Zealand) suggests a mean paraffinic oil potential of ∼85 kg/t C (range ∼70–130 kg/t C), based on n-alkane/alkene generation in the C 6–C 31 range and typical proportions of these compounds in related oils from New Zealand. This maximum in the depth trend of pyrolysate yield is reached at ∼0.75–0.80% R 0, comparable to the previously reported maximum in hydrogen index (HI). Thermal extraction–GC (TE–GC) provided higher yields than Rock-Eval S1pyrolysis, but without the uniform trend exhibited by S1/C below the ∼3.0 km below sea floor (∼0.75–0.80% R 0) onset of expulsion. In addition, the saturates:aromatics ratio in the thermal extract decreased with depth, indicating preferential retention of aromatics, which may affect the expulsion efficiency of paraffins. Thermal extracts suggest that at most ∼15 kg/t C of paraffinic oil is retained within the Tara coals, which is lower than previous estimates of saturation threshold. However, it is likely to be adversely affected (lowered) by loss of the least volatile components during recovery and storage of cuttings and incomplete recovery of high molecular weight components (particularly C 40+ paraffins) using TE–GC. Isopimarane generation appears to be restricted to the depth zone corresponding to the early oil window, although it is unclear whether this is directly related to the maturity range required for such generation or that only the latest Cretaceous coals in Tara-1 exhibit particularly high abundances of such gymnosperm-derived diterpanes.

Adsorption of basic dyes from aqueous solution onto activated carbons

Abstract The aim of this research is to compare the adsorption capacity of different types of activated carbons produced by steam activation in small laboratory scale and large industrial scale processes. Equilibrium behaviour of the activated carbons was investigated by performing batch adsorption experiments using bottle-point method. Basic dyes (methylene blue (MB), basic red (BR) and basic yellow (BY)) were used as adsorbates and the maximum adsorptive capacity was determined. Adsorption isotherm models, Langmuir, Freundlich and Redlich–Peterson were used to simulate the equilibrium data at different experimental parameters (pH and adsorbent particle size). It was found that PAC2 (activated carbon produced from New Zealand coal using steam activation) has the highest adsorptive capacity towards MB dye (588 mg/g) followed by F400 (476 mg/g) and PAC1 (380 mg/g). BR and BY showed higher adsorptive affinity towards PAC2 and F400 than MB. Under comparable conditions, adsorption capacity of basic dyes, MB, BR and BY onto PAC1, PAC2 and F400 increased in the order: MB

06/02512 Comparison of the R70 self-heating rate of New Zealand and Australian coals to Suggate rank parameterBeamish, B. B. International Journal of Coal Geology, 2005, 64, (1–2), 139–144

06/02512 Comparison of the R70 self-heating rate of New Zealand and Australian coals to Suggate rank parameterBeamish, B. B. International Journal of Coal Geology, 2005, 64, (1–2), 139–144

Study on the suitability of New Zealand coals for hydrogen production

Internationally there is considerable interest in utilizing hydrogen as an energy carrier. The use of hydrogen offers considerable potential benefits such as reducing greenhouse emissions, reducing urban pollution, increased energy security and increased efficiencies from the use of advanced energy conversion technologies. One of the most important questions when considering the development of a hydrogen economy is “where will the hydrogen come from?” Possible answers include electrolysis of water, steam reforming of methane and the gasification of coal. Given the high costs associated with electrolysis of water, and the increase in the cost of methane predicted over time, the gasification of coal is viewed by many as being the cheapest method of hydrogen production in the foreseeable future. These considerations are particularly relevant to New Zealand where gas supplies are dwindling but where there is sufficient coal to last for many centuries at present utilization rates. This, along with the current high international interest in hydrogen energy, has been recognized by the New Zealand Government in the form of a six-year [2002–2008] research project “Hydrogen Energy for the Future of New Zealand”. One important coal property that, in particular, determines the suitability of a particular coal for use in a fluidised bed gasifier is its reactivity towards the gasification reaction. It was found that a high percentage of New Zealand's coal resource is particularly well-suited towards fluidised bed gasification, reacting at anywhere between 0.9 to 1.75 times the rate of Australian brown coals. It was found the New Zealand lignites contained significant levels of organically bound calcium, which was shown to be responsible for not only the high reactivity of the New Zealand lignites, but also a product gas composition with higher than expected hydrogen concentrations. These findings are discussed along with their implications for the gasifier and gas clean-up design.

03/02105 Maturity-related variation in the bulk-transformation kinetics of a suite of compositionally related New Zealand coals: Killops, S. et al. Marine and Petroleum Geology, 2002, 19, (9), 1151–1168

03/02105 Maturity-related variation in the bulk-transformation kinetics of a suite of compositionally related New Zealand coals: Killops, S. et al. Marine and Petroleum Geology, 2002, 19, (9), 1151–1168

Carbon NMR of coals: the effects of coal type and rank

Carbon-13 nuclear magnetic resonance (NMR) spectra, which provide direct measurements of the chemical structure of organic matter, have been obtained for a large number of New Zealand coals ranging from peat to semi-anthracite. Converted into numerical parameters, the spectra show differences related to coal type and rank. Four NMR parameters— f a, S ox, f CO2H and f COH—are examined, whereas only f a is commonly treated in previous publications. Previously, the effects of coal type have not been considered in interpreting whole-coal samples, although f a had been shown to vary inversely with hydrogen content in the lower rank coals. A wide variety of analytical determinations were used as rank indicators. In the present study, Rank( S r), which is type-compensated, is used as the principal rank index; T max and reflectance are also considered. Coals within the middle one-third of the New Zealand Coal Band, representing a restricted type range of moderately high hydrogen coals, exemplify the changes in NMR parameters as rank increases. These are all particularly sensitive to the earliest changes in kerogen, when the distinguishing oxygenated functional groups are abundant, both within the peat and as peat changes to the lowest-rank lignite. As rank increases, both f CO2H and f COH progressively decline, but neither f a nor S ox shows such uniform change. In particular, inflections in the f a/Rank( S r) and S ox/Rank( S r) curves closely correspond, for New Zealand coals, to the onset of oil expulsion and the culmination (before rapid decline) of coal coking properties.