Preparation and characterization of a zeolite from rice hull ash and an investigation of its catalytic properties

Date

3-2003

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Milagros M. Peralta

Abstract

Purification of the rice hull ash was accomplished b) acid digestion followed by thermal treatment and resulted to a concentrated Si and Al content in the ash sample. The percentage recover) of the ash after the purification process was about 90.63 % weight per weight basis. The scanning electron micrographs of the untreated and purified rice hull ash showed that the purification did not affect the amorphous nature of the silica contained in the ash. Moreover, it resulted to finer particles, as observed by the difference in the estimated particle sizes. about 2 14 mm and 214 pm for the untreated and purified ash. respectively

The zeolite was synthesized hydrothemally at 100-110°C, using a basic reaction gel consisting of the rice hull ash as the main silica and alumina source. tetramethylammonium iodide as the template and water. The best yield for the synthesis was about 117'9.. The synthesized zeolite was of the high-silica type. with Si/AI ratios of about 8.06. 59.116. and 81.99 for the as-synthesized, activated (Nail.), and active acid Ili-) form. respectively-. The adsorption property of the 11-form zeolite was approximately quantified as cation exchange capacity (CE(7), with a value of 0.6237 ± 0.0135 meq/ g sample. The infrared analysis of the 11-form zeolite was characteristic of a tetrahedral trantewitti of ISiO414- and (M0,1` units with bridging 1)11 groups.. Also, the spectrum showed that the sample had adsorbed considerable amounts of water. The scanning electron micrographs of the said form of zeolite demonstrated that the particles were really an agglomeration of smaller crystals. the particle size for the zeolite was calculated at 2.22-14.6 nm.

The catalytic properties of the active acid form of the zeolite was determined and compared with that of the mineral acid. 1004, in the hydration reaction of cyclohexene to cylohexanol use product yield for cyclohexanol using the zeolite was low under the conditions used but still greater than that of the mineral acid. Kinetic studies of the hydration reaction showed that there was a higher rate of product formation for the zeolite-catalized traction. which was found to he independent of the zeolite concentration.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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