The Order of Confirmation has two principal forms of the liturgy (1 &2). Chapter 3 offers a brief couple of notes for when a bishop (who is the Ordinary minister of Confirmation) does not preside. Chapter 4 gives a shortened form of the Order.
The Introduction to the Order of Confirmation indicates the following reasons why Confirmation may be celebrated without Mass:
As a rule, Confirmation takes place within Mass so that the fundamental connection of this Sacrament with all of Christian Initiation, which reaches its culmination in the Communion of the Body and Blood of Christ, may stand out in a clearer light. The newly confirmed therefore participate in the Eucharist, which completes their Christian Initiation.
If, however, the candidates for Confirmation are children who have not received the Most Holy Eucharist and are not being admitted to First Communion at this liturgical celebration or if other special circumstances so suggest, Confirmation should be conferred outside Mass. Whenever Confirmation is conferred without Mass, a celebration of the word of God should precede it. [OC 13]
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